Advanced Modeling and Simulation (AMS) Seminars

Previous Topics in the AMS Seminar Series

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• 11/05/2026 Two-Phase Shear Layers and Liquid Sheet in an Airstream in the Compressible RegimeZoe Barbeau, Flow Physics and Aeroacoustics Laboratory, Stanford UniversityThis presentation covers the extension of a high-order compact finite difference framework to compressible, two-phase flows for simulation of atomization and the study of temporal two-phase shear layers and liquid sheets in an airstream. The effect of compressibility on two-phase shear layers and liquid sheets in an airstream is examined in the linear regime through linear stability analysis and by simulation with the compact scheme framework in the nonlinear regime.
• 10/29/2026 Local, Matrix-Free Divergence Cleaning for High-Order MHDDongwook Lee, Department of Applied Mathematics, University of CaliforniaThis seminar presents a fifth-order accurate multidimensional finite volume MHD scheme based on a divergence-cleaning projection method. The new cleaning method numerically preserves the solenoidal constraint on the magnetic field. This projection method utilizes a new hyperbolic-variant successive over-relaxation (SORh) iteration designed specifically to solve the Poisson equation arising in the projection step.
• 10/27/2026 Curvilinear Gridding and Connectivity Best Practices within the LAVA FrameworkJames Koch, Computational Aerosciences Branch, NASA Ames Research CenterThis presentation will discuss best-practices in constructing grid topologies for the LAVA curvilinear solver, as well as the suite of tools available to alleviate and streamline user gridding and domain connectivity effort.
• 10/15/2026 On the Construction of High-Order and Exact Pressure Equilibrium Schemes for Arbitrary Equations of StateNguyen Ly, Analytical Mechanics Associates/NASA Ames Research CenterBlurb.
• 09/24/2026 A Strain-Consistent Epsilon-Based Flamelet Model for Non-Premixed Turbulent CombustionSylvain L. Walsh, University of California, IrvineThis talk examines a strain-rate inconsistency in the conventional flamelet/progress-variable (FPV) formulation for non-premixed combustion and proposes an alternative coupling based on the turbulent kinetic energy dissipation rate, ε. Two-dimensional RANS simulations of a transonic accelerating reacting mixing layer are performed using one-step finite-rate chemistry, a conventional FPV model, and the proposed ε-based flamelet model.
• 08/20/2026 Differentiable Surface Mesh Deformation for Large-Scale MDO of Aircraft ConceptsMarius Ruh, University of California, San DiegoThis talk presents a differentiable surface mesh deformation methodology for large-scale multidisciplinary design optimization of aircraft concepts undergoing large geometric changes. The approach combines explicit parametric geometry with implicit signed-distance-function representations to update conforming surface meshes for independently parameterized and intersecting aircraft components.
• 08/13/2026 Enhancing Non-Linear PDE Solver Convergence with Learnable ModelsJennifer Abras, Bowhead Total Enterprise Solutions LLCThis seminar will describe a fully encapsulated graph neural network (GNN) methodology that learns the residual to solution mappings as the solver executes and applies the trained model predictions to warm start the solver iterations. Both the non-linear and linear solver stages utilize an independently trained GNN, and all stages of the data curation and training are executed as the simulation runs.
• 08/06/2026 Integrated Propulsion System Modeling for Advanced Aircraft Using Multidisciplinary Design OptimizationAnushka Tahiliani, MIT Gas Turbine LaboratoryThis talk presents an optimization-oriented propulsion modeling framework for integrated aircraft conceptual design. Parametric turbofan, turboshaft, and fan models are implemented in NASA's OpenMDAO environment using pyCycle and organized within a unified propulsion-system formulation.
• 07/23/2026 An AI-Driven Design RevolutionDarcy Allison, Anduril Industries and Jeffryes Chapman, NASA Glenn Research CenterThis seminar will present Anduril Industries' approach to Artificial Intelligence and how it is transforming defense capabilities with advanced technologies. As the world enters an era of strategic competition, Anduril delivers cutting-edge autonomy, AI, computer vision, sensor fusion, and networking technology to the warfighter in months, not years.
• 07/16/2026 A Multi-GPU-Accelerated Sharp-Interface Immersed-Boundary Solver for Extreme-Scale Flow Simulation with Moving BoundarySushrut Kumar, Johns Hopkins UniversityThis seminar will describe the development of a fully GPU-resident, multi-GPU version of the sharp-interface immersed boundary solver ViCar3D and the algorithmic innovations that make extreme-scale fluid–structure interaction (FSI) simulations practical.
• 07/09/2026 Multi-Fidelity Aerodynamic Surrogate Modeling for Conceptual Design Using Graph Neural NetworksYiren Shen, Stanford UniversityThis talk presents MF-VortexNet, a multi-fidelity aerodynamic surrogate framework that uses graph neural networks to learn field-level corrections to low-fidelity pressure predictions from high-fidelity CFD data. By operating on pressure-field information, MF-VortexNet improves interpretability, enables the evaluation of arbitrary aerodynamic quantities, and supports generalization across a prescribed design space.
• 07/02/2026 Transonic Buffet Alleviation via Linear Stability AdjointRohit Sunil Kanchi, University of Tennessee, KnoxvilleIn this talk, the speaker will present a coupled adjoint framework for buffet-constrained aerodynamic optimization and buffet alleviation. The method efficiently computes sensitivities of the dominant linear stability analysis eigenvalue with respect to shape design variables.
• 06/25/2026 Second-mode Waves in Hypersonic Transition: Energy Balance, Kinematics and MechanicsCarlo Scalo, Defense Sciences Office, DARPAThis seminar presents recent advances in the understanding of the fundamental structure of second-mode waves in hypersonic transition published by Roy & Scalo, J. Fluid Mech. (2025-2026).
• 06/04/2026 A Predictive Wall Model for Laminar-Turbulent Transition for Large-Eddy SimulationCarlos A. Gonzalez, Johns Hopkins University Applied Physics LaboratoryThis seminar will propose a nonlinear parabolized stability equations (NLPSE) in conjunction with WMLES to simulate transitional flows affordably and accurately. Falkner-Skan wall model for the simulation of laminar flow fields on coarse grids and a PSE-Sponge method will be discussed.
• 05/28/2026 High-Speed Reactive Flow Simulations on Exascale Systems: Applications to Rocket CombustorsAlbo Voci, Flow Physics and Aeroacoustics Laboratory, Stanford UniversityThis presentation focuses on the use of collocated, high-order finite difference schemes in multiblock grids. In the presence of grid singularities, it is shown that the geometrical conservation laws, governing the numerical relation between the mesh and the metrics (surface and volume properties), are not satisfied.
• 05/21/2026 The Numerical Methods of John von Neumann and How They Led to Hypersonic CFDRussell M. Cummings, US Air Force AcademyThe history of computational fluid dynamics (CFD) has been intertwined with the history of numerical methods and calculation capabilities for decades. Those connections are perhaps no stronger than when looking at the development of numerical methods and calculation approaches that could simulate shock waves due to the discontinuity that exists across the shock.
• 04/30/2026 Observations from Forty Years at NASA, the NAS Facility, and the Growth of CFDStuart Rogers, NASA AmesOver forty years ago Stuart Rogers started working on at NASA Ames, focusing on research in computational fluid dynamics (CFD). Stuart was among the first users of the new Numerical Aerodynamic Simulation (NAS) facility (now known as the NASA Advanced Supercomputing facility). On the eve of his retirement, Stuart reflects on forty years as a NAS user and on the growth of CFD from research to application.
• 04/23/2026 Advances in Grid Algorithms for Weather and Climate Models: From Local Refinement to Global CouplingJoseph Mouallem, Princeton UniversityThis presentation highlights recent advances in grid design and model coupling within next-generation Earth system models at GFDL/NOAA. It will discuss two-way grid nesting strategies in NOAA's dynamical core FV3 that enable targeted high-resolution refinement while maintaining consistency with the global solution.
• 04/09/2026 Perspectives on Foundation Models and Agentic Architectures for Computational Fluid DynamicsNeil Ashton, NVIDIAThe integration of AI into computational fluid dynamics (CFD) represents a transformative frontier for engineering, yet realizing this potential requires navigating the complexities inherent to fluid mechanics. Bridging the methodological gap between deep learning and traditional CFD simulation, this talk presents work to produce a novel scaling law tailored specifically for a fluids foundation model.
• 04/02/2026 Sub-Filter-Scale Shear Stress Deficit in Hypersonic Wall-Bounded Turbulence and Its Implications for Large-Eddy SimulationTakahiko Toki, Purdue UniversityIn this talk, the limitations of current LES models are first illustrated through simulations of hypersonic conical boundary layers. The focus then shifts to sub-filter-scale (SFS) turbulent behavior, investigated using direct numerical simulations (DNS) of hypersonic Couette flow with particular attention to shear-stress components.
• 03/26/2026 Using Anisotropic Mesh Adaptation to Automate Computation of Multifidelity Aerodynamic Databases for Flight-Dynamics AnalysisAnthony Ricciardi, ATA Engineering, Inc.An autonomous process for creating surrogate aerodynamic models for flight-dynamics analysis is developed. Provided with only the vehicle’s geometry and operating envelope, the process automatically selects multifidelity analysis conditions for inviscid and viscous aerodynamic analysis, creates meshes from the vehicle geometry, and ensures accuracy of computational solutions using state-of-the-art mesh-adaptation methods.
• 03/19/2026 Advancements and Challenges in Aerodynamic Simulations in the Age of GPU ComputingFlorian Menter, Synopsys Fellow, ANSYS Germany GmbHThe availability of GPU hardware has initiated a transition from classical RANS-based methods to Scale-Resolving Simulation approaches in a wide range of industrial applications. A central target area is external aerodynamics, with a focus on aeronautics and automotive applications. The talk will lay out the strategy and the different elements with which Synopsys approaches these challenges using the Ansys suite of CFD solvers.
• 03/12/2026 High-Fidelity Simulations of Noise and Performance Induced by Time-Harmonic Gust Interaction with eVTOL RotorVadim Voropayev, Embry-Riddle Aeronautical UniversityUrban Air Mobility demands accurate noise prediction for electric vertical take-off and landing (eVTOL) aircraft, particularly regarding the aeroacoustic response of rotors to unsteady inflow, such as atmospheric turbulence within the city, that can be mathematically decomposed into a superposition of distinct modes, each having a varying degree of aerodynamic impact.
• 03/05/2026 Discovery of Unstable SingularitiesJavier Gómez-Serrano, Department of Mathematics, Brown UniversityThis talk will explain how to numerically construct several new unstable singularities to certain equations in fluids (CCF, IPM, Boussinesq) using machine learning methods.
• 02/25/2026 Aerodynamic Optimization of a Cruise-Slotted Transonic Truss-Braced-Wing Aircraft ConfigurationTimothy Chau, Analytical Mechanics Associates, NASA Ames Research CenterThis seminar investigates the aerodynamic design and performance of a cruise-slotted transonic truss-braced-wing configuration through the application of aerodynamic shape optimization based on the Reynolds-Averaged Navier-Stokes equations.
• 02/12/2026 Large-Eddy Simulation of an Iced Swept Wing: A Perspective on the Aerodynamic Effect of Triggering Resolved TurbulenceDavid Craig Penner, Analytical Mechanics Associates, NASA Ames Research CenterBuilding on the success within the CFD community of using large-eddy simulation (LES) to accurately capture the aerodynamics of clean wings near stall, LES of a swept wing with leading-edge ice buildup is performed using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) framework and compared to experimental results.
• 02/05/2026 Cartesian Cut-cell Methods for High Reynolds Number FlowsAlex Kleb, Analytical Mechanics Associates, NASA Ames Research CenterThis work will show that an ordinary differential equation (ODE) wall function incorporating pressure-momentum balance enables accurate high Reynolds number viscous flow predictions on coarse Cartesian cut-cell meshes with the RANS equations. The ODE can achieve correct skin friction predictions on meshes more than four times coarser than analytical wall functions require.
• 01/29/2026 Large-Eddy Simulations of Conjugate Heat Transfer over Iced SurfacesFederico Zabaleta, Center for Turbulence Research, Stanford UniversityThe accurate prediction of aircraft icing remains a critical challenge for flight safety and certification. While various ice accretion codes are currently in use, they frequently exhibit significant uncertainty, particularly in glaze ice conditions. This talk presents a high-fidelity, multi-physics framework that integrates wall-modeled large-eddy simulation (WMLES), Lagrangian droplet tracking, and unsteady conjugate heat transfer (CHT) to resolve coupled fluid-solid thermal interactions.
• 01/22/2026 Progress in Lattice Boltzmann Schemes: Mesh Adaptation, High-Order Accuracy, Numerical Analysis, and Boundary ConditionsThomas Bellotti, Université Paris-SaclayThis talk will cover several selected topics related to recent advances in lattice Boltzmann (LBM) schemes achieved over the past few years, from both practical and theoretical perspectives. Lattice Boltzmann methods are widely used—particularly in computational fluid dynamics—because of their computational efficiency, excellent parallelizability, and ease of implementation for complex problems.
• 12/18/2025 Construction of High-Order and Exact Pressure Equilibrium Schemes for Arbitrary Equations of StateChristopher DeGrendele, Computational Aerosciences Branch, NASA Advanced Supercomputing DivisionTypical fully conservative discretizations of the Euler compressible single or multi-component fluid equations governed by a real-fluid equation of state exhibit spurious pressure oscillations due to the nonlinearity of the thermodynamic relation between pressure, density, and internal energy. A fully conservative, pressure-equilibrium preserving method and a high-order, fully conservative, approximate pressure-equilibrium preserving method are presented.
• 12/11/2025 Smarter Grids, Faster Solvers: Advances and Applications with NASA’s Cart3DMichael J. Aftosmis, Computational Aerosciences Branch, NASA Advanced Supercomputing DivisionCart3D is one of the most widely used high-performance aerodynamic simulation packages in NASA’s software catalog, with hundreds of users across NASA and the U.S. aerospace industry. This seminar provides an overview of the software’s design goals and core technologies, with an emphasis on automation, robustness, and solution accuracy.
• 12/04/2025 Sample-Efficient and Principled Aerospace Decision-Making with Small DataAshwin Renganathan, Pennsylvania State UniversityThis talk will address problems anchored in, what we coin, the “decision-making triad” which includes: surrogate modeling, uncertainty quantification (UQ), and numerical optimization/control. Specifically, using variants of a probabilistic surrogate model and a Bayesian decision theoretic framework, we will show that problems in the decision-making triad can be solved in a principled, theoretically sound and, yet (computational) cost-effective manner.
• 09/25/2025 Supervised vs. Unsupervised Learning for First Order Hyperbolic Nonlinear PDEsAlexandre Bayen, University of California, BerkeleyThis talk investigates the use of neural networks as discrete approximations of first order nonlinear hyperbolic partial differential equations (PDEs). Two approaches are considered. The first is a supervised approach, performed on solutions of a training set composed of Riemann problems. The second approach, unsupervised, follows the physically inspired neural network approach, in which a loss function based on the initial PDE is used to train the neural network.
• 09/18/2025 Machine Learning Surrogates and Bayesian Optimization in Turbomachinery Structural DesignKristopher Pierson, NASA Glenn Research CenterThis seminar addresses two related topics: machine learning surrogate model accuracy in turbomachinery structural design and the application of Bayesian optimization. The first section examines how choices such as surrogate model type, the number of design variables, the training sample size, and the depth of neural network architectures affect predictive accuracy, with results validated against finite element analysis. The second section introduces Bayesian optimization, including an overview of three acquisition functions and demonstrations on two example problems.
• 08/26/2025 The Viscous Vortex Particle Method for Wake Modeling of Mars RotorcraftTove Ågren, Analytical Mechanics Associates, NASA Ames Research CenterThis seminar will discuss the application of the Viscous Vortex Particle Method (VVPM) as a mid-fidelity tool for simulating rotor wakes of Mars rotorcraft. The talk will present validation results against Ingenuity hover and forward-flight data, highlight how VVPM captures coaxial interference and unsteady loading, and extend the discussion to next-generation multi-rotor designs such as a Mars hexacopter.
• 08/21/2025 Simulation of Turbulent Flows Using the Dynamic Hybrid RANS-LES (DHRL) ModelTausif "TJ" Jamal, Configuration Aerodynamics Branch, NASA Langley Research CenterThe Dynamic Hybrid RANS-LES (DHRL) modeling framework was developed to provide the user with the ability to combine any Reynolds-averaged Navier-Stokes (RANS) model with any Large Eddy Simulation (LES) model based on the ratio of resolved to modeled stresses ensuring a continuity in turbulence production. This seminar will highlight the performance of the DHRL model for a few test cases including its application for non-stationary flows.
• 07/31/2025 Towards a New Approach of Mesh Adaptation Methods and its Impact on Accuracy for the Simulation of Stiff PDEsMarc Massot, Centre de Mathématiques Appliquées, École PolytechniqueThis presentation will address the objective of accurately simulating multi-scale PDEs in time and space at a reasonable cost. This leads to the use of dynamic mesh adaptation and dedicated numerical schemes. The main focus for this seminar is on examining the impact of mesh adaptation on the accuracy of the solution.
• 07/29/2025 High-Order Adaptive Multistep Code CouplingLaurent François, ONERAThis talk will present a novel temporal coupling strategy, the multistep coupling scheme, which aims at providing high-order accuracy in time for the coupling terms, as well as a dynamic error-based adaptation of the coupling time step. The theoretical foundation of the scheme will be presented.
• 07/17/2025 Managing Large CFD Run Matrices and MoreDerek Dalle, Computational Aerosciences Branch, NASA Ames Research CenterThe focus of this seminar will be on the new capabilities of CAPE, including validation of its main input files, asynchronous data processing during CFD execution, and direct interaction with volume data (thanks in part to PyVista).
• 07/10/2025 Accelerating CFD with Modular Surrogates: Insights from MeshGraphNets and UPT ArchitecturesViktor Rozsa, RescaleThis seminar will describes a modular surrogate-modeling framework built on Nvidia PhysicsNemo and other open-source frameworks that use MeshGraphNets and Universal Physics Transformer models on representative CFD cases, highlighting trade-offs in accuracy, inference speed, generalization to new geometries, and integration into standard CAE pipelines.
• 07/01/2025 Grid-Adaptation for Large Eddy Simulations: A Sequence of Ideas over 10+ YearsJohan Larsson, University of Maryland, College ParkWhile grid-adaptation has reached a certain level of maturity in several areas of CFD, the application to turbulence-resolving simulations (most notably, large eddy simulations) is still in its infancy. This talk will discuss some progress made to address some of the challenges of turbulence-resolving simulations over the last 5-10 years, along with outstanding issues and ongoing/future work.
• 06/26/2025 On the Application of an Actuator Line Model for Rotorcraft Outwash PredictionsNicholas Peters, Aeromechanics Office, NASA Ames Research CenterThis study investigates the implementation of a new actuator line model within NASA’s OVERFLOW computational fluid dynamics (CFD) solver, focusing on predicting rotorcraft outwash.
• 06/17/2025 Computationally Efficient 3D Radiation and a Recipe for Multi-physics Hypersonic SimulationsAmal Sahai, Analytical Mechanics Associates, Inc., NASA Ames Research CenterThis talk focuses primarily on computationally efficient radiative calculations to demonstrate how the marriage of physics-based reduced-order modeling and novel numerical methods can pave the way for realizing predictive simulations for practical design problems.
• 06/12/2025 LAVA: A NASA Mission-Critical CFD Solution - Gearing Up for Public ReleaseMichael Barad, Jeffrey Housman, Emre Sozer, and Jared Duensing, NASA Ames Research CenterSince its inception over 15 years ago, the Launch, Ascent, and Vehicle Aerodynamics (LAVA) CFD Framework has evolved into a highly performant and comprehensive multi-physics simulation suite. This talk will detail recent advancements within LAVA, highlight key application results, and introduce new design optimization tools.
• 05/15/2025 An Efficient Data-Driven Approach for Assessment and Selection of Reynolds-Stress-Equation Closure ModelsAli Mani, Stanford UniversityThis seminar presents an approach for systematic generation of reference data that can economically sample diverse regions in the parameter space. This approach is based on the Macroscopic Forcing Method and its extension for second moment closures in which volumetric forcing terms and boundary conditions are utilized to diversify the sampled flow conditions.
• 05/08/2025 Near-Wall Modeling for Rough-Wall Turbulent Boundary Layer Flows with Heat TransferXiang Yang, Pennsylvania State UniversityThis talk presents recent progress in near-wall modeling for rough-wall turbulent boundary layer flows with heat transfer, in the context of wall-modeled large-eddy simulation (WMLES).
• 05/01/2025 Advancements in Coupled Aeropropulsive Design OptimizationM. A. Saja Abdul-Kaiyoom, University of MichiganThis seminar will demonstrate two aeropropulsive coupling methods in computational fluid dynamics-based models that simulate the coupled effects of the propulsion system and the airframe using an over-wing nacelle configuration, which has the potential to improve on the conventional under-wing nacelle configuration by enabling higher bypass ratios and increasing noise shielding.
• 04/24/2025 Next-Gen Graphics Performance: How Vulkan Transforms Tecplot 360 and FieldView for Faster, Smarter CAE Post-ProcessingScott Fowler and Yves-Marie Lefebvre, Tecplot, Inc.For the past year, Tecplot has been working on a new graphics engine to achieve faster performance, increase memory efficiency, and leverage modern rendering techniques. Tecplot 360 and FieldView will be among the first CAE applications to leverage the power of Vulkan for optimized graphics performance. This webinar will give a technology preview of the new graphics engine for both Tecplot 360 and FieldView.
• 04/10/2025 Solving Forward and Inverse Problems in High-Speed Boundary Layers Using Machine LearningYue Hao, Johns Hopkins UniversityThis presentation will show how DeepONets (deep neural network architectures designed to approximate operators) can be used to address mapping an incoming perturbation to its corresponding downstream field accurately, and determining the original perturbation from downstream measurements.
• 03/27/2025 Rotor Design for Mars Helicopters: Overcoming Aerodynamic Challenges for Future Mars ExplorationWitold Koning, NASA Ames Research CenterThis presentation explores recent aerodynamic advancements in rotor design for the Martian environment, including unconventional airfoils and coupled airfoil-rotor optimization. Wind tunnel testing and computational studies reveal the limitations of maintaining laminar flow over the airfoil and underscore the need for innovative airfoil design approaches.
• 03/20/2025 PyVista for CAE Datasets: Streamlining 3D Visualization and AnalysisAlex Kaszynski, Pasteur ISI and AFRL/USAFThe PyVista software suite includes several Python libraries designed to simplify 3D visualization and mesh analysis by providing a streamlined interfaces to a variety of performant C++ libraries. This presentation explores PyVista’s capabilities, including its integration with VTK, ease of use compared to raw VTK workflows, and its applicability to CAE datasets.
• 03/13/2025 Intelligent and Progressive Scientific Data ManagementQing Liu, New Jersey Institute of Technology / X-Byte ResearchThis talk aims to address the issue of I/O bottleneck for data analytics over parallel storage systems, which are shared by multiple applications in a non-exclusive manner.
• 03/06/2025 Modeling, Simulations, and Analysis of Turbulent Boundary Layers Exhibiting Smooth Body SeparationRahul Agrawal, Ph.D. Candidate, Stanford UniversityThis talk will discuss utilizing the large-eddy simulation (LES) paradigm to study the phenomenon of incipient, smooth body flow separation over complex geometries.
• 02/27/2025 Stability Analysis and Improvement in Computational Fluid DynamicsMohammad Zandsalimy, The University of British ColumbiaA novel method for enhancing the numerical stability of computational simulations via mesh optimization is introduced. This technique employs Dynamic Mode Decomposition to approximate the evolution of non-linear solutions as a linear mapping, effectively reducing the system’s degrees of freedom.
• 02/20/2025 High-Performance, Productive Programming using Chapel with Examples from the CFD Solver CHAMPSEngin Kayraklioglu, Hewlett Packard Enterprise; Eric Laurendeau, M. Karim Mohamad Zayni, Polytechnique MontrealChapel is a general-purpose programming language that makes parallel programming far more productive than conventional approaches. Chapel promotes scalable parallelism, permitting code to be developed using a laptop’s multi-core processor, and then recompiled to run across the nodes and cores of a commodity cluster, cloud instance, or massive-scale supercomputer.
• 02/06/2025 Directed Energy and the Optical Effects of FluidsSteven La Cava, Ansys Government InitiativesDirected energy systems are complex involving multiple physics, including fluids, mechanics and optics. Some of these effects can be mitigated through cooling, however, cooling such systems is a complex endeavor. This webinar seeks to illustrate the modeling of such systems and compare against known public results.
• 01/30/2025 Liutex – The Past, Current, and FutureChaoqun Liu, University of Texas at ArlingtonLiutex is a rigorous and mathematical definition of local fluid rotation or vortex, given in 2018 for the first time in history. Since the vortex is omnipresent in the universe, the introduction of Liutex will benefit researchers in almost all fluid-related research areas including aerodynamics, hydrodynamics, meteorology, bio flow, space science, etc.
• 01/23/2025 Recent Development and Applications of the EPOGS Toolset for Automatic Structured Overset Mesh GenerationWilliam M. Chan, Computational Aerosciences Branch, NASA Ames Research CenterThis talk will present recent testing of the overset mesh generation automation software toolset EPOGS on sever applications. These include various VTOL concept vehicles, mesh families for multiple CRM configurations, and component increment and positioning studies.
• 01/16/2025 Multi-Fidelity Aerodynamics Surrogate Modeling Using SageAndrew Wissink, US Army DEVCOM Aviation & Missile Center, NASA Ames Research CenterThis talk will discuss efforts to integrate higher fidelity computational methods into trade space analysis using fast-running surrogate models. The DoD’s High Performance Computing Modernization Program recently initiated the development of Sage, a production surrogate model generation software intended for engineers accustomed to running CFD codes.
• 12/19/2024 Energy Transfer Mechanisms in Wall-Bounded Turbulent Flows using Generalized Quasilinear ApproximationsCarlos Gonzalez Hernandez, Stanford UniversityThis talk will analyse the spectral energetics of a quasilinear-type model applied to a homogeneous shear turbulent flow and channel flow, in particular its effect on the energy cascade and the damage of the pressure-strain transport.
• 12/17/2024 SALT-FM and TAU for Performance Analysis, Profiling and BeyondSameer Shende, University of Oregon and ParaTools, Inc.This talk will present recent advances in the TAU Performance System and also discuss work on SALT-FM under a NASA Phase I SBIR award. SALT-FM is the Source Analysis Toolkit for Fortran and Mixed-Language Software.
• 12/12/2024 Development of Aerodynamic Shape Optimization Capability within NASA's LAVA FrameworkBrandon Lowe, Science and Technology Corporation/NASA Ames Research CenterThis seminar will present the current methodologies and tools within the LAVA framework for aerodynamic shape optimization, highlight recent advancements, and discuss future directions for enhancing its capabilities. Key components used in the shape optimization process will be discussed, including the flow solver, gradient calculation techniques, geometric parameterization, and mesh deformation strategies.
• 11/14/2024 Implicit Preconditioning for Explicit Multigrid Solvers on Cut-Cell Cartesian MeshesJonathan J. Chiew, NASA Ames Research CenterCut-cell Cartesian methods enable automated mesh generation and adaptation which are essential for vehicle design and optimization. However, optimizations may slow down or terminate if the solver is not able to converge. In this talk, we discuss an investigation into implicit preconditioning for strengthening the explicit multigrid solver utilized in the Cart3D simulation framework. A Jacobian-free Krylov subspace method is employed to solve the linear preconditioning equations, demonstrating improved multigrid convergence rates on a variety of problems.
• 11/07/2024 A Scalable Platform for Rapid Data Analytics Through Data Driven Lossy CompressionBen O’Neill, RNET Technologies & Rohit Deshmukh, Florida Atlantic UniversityIn this talk we present recent advancements in data-driven lossy compression using Data-informed Local Subspaces, including a “delayed” compression approach that minimizes online (in situ) compression costs, a “zone-based” compression algorithm that lowers compression costs and caps memory usage, and a new error-bounded lossy compression approach that can be applied on both structured and unstructured data.
• 10/31/2024 Progress Towards Modeling Hypersonic Fluid-Structure Interactions with Large Structural DeformationsMadeline Peck, Los Alamos National LaboratoryThis talk will outline a new approach to modeling fluid-structure interactions by combining discontinuous Galerkin and material point methods.
• 10/24/2024 Scalable Parallel Linear Solver for Compact Banded SystemsHang Song, Stanford UniversityThis talk will present a direct parallel linear solver algorithm for the banded linear systems arising from compact numerical schemes.
• 10/17/2024 Turbulence Anisotropy Modeling Based on the Quadratic Constitutive Relation (QCR) Using LES Flow DatabasesYoshiharu Tamaki, University of TokyoThis presentation introduces the recent development of a new QCR based on the large-eddy simulation of a side-wall interference flow at a high Reynolds number. The developed model (QCR2024) is validated through a priori tests of various flows, where the results show improved prediction of the Reynolds stress anisotropy.
• 10/08/2024 LAVA Voronoi Mesher for Wall-Modeled Large-Eddy SimulationsVictor C. B. Sousa, Science and Technology Corporation/NASA Ames Research CenterIn this presentation the unstructured Voronoi mesher currently being developed within the Launch, Ascent, and Vehicle Aerodynamics (LAVA) software framework at NASA Ames Research Center is described in detail.
• 09/26/2024 Evaluation of a Physics-Based Unsteady RANS Method for Buffet Onset PredictionJeffrey A. Housman and Daniel Maldonado, NASA Ames Research CenterThis seminar will discuss a physics-based moving-body unsteady Reynolds-Averaged Navier-Stokes-based method for predicting the onset of transonic buffet using four cases of varying complexity.
• 09/19/2024 Computational Analysis of a Boundary Layer Ingesting Tailcone Thruster Configuration Using the LAVA Curvilinear SolverLuis S. Fernandes, NASA Ames Research Center and David T. Chan, NASA Langley Research CenterNASA conducted an experimental campaign to study the propulsion-airframe integration effects of boundary layer ingesting propulsion systems. This talk will cover the combined experimental and numerical efforts that resulted.
• 09/12/2024 The Discrete Adjoint Solver in SU2 and its Application to Multiphysics ProblemsOle Burghardt, University of Kaiserslautern-LandauThe discrete adjoint solver in the open-source software SU2 is one of its integral and well-established functionalities. This talk will go through some main aspects of the implementation and we point out how multiple discrete adjoint solvers are combined in the case of multi-disciplinary problems.
• 09/05/2024 Using OpenVSP Models in the Engineering Sketch PadJohn F. Dannenhoffer, III, Syracuse UniversityThis seminar discusses a new capability in which OpenVSP models can be used directly in Engineering Sketch Pad, and subsequently in CAPS. This coupling allows ESP to directly drive OpenVSP's user parameters and to generate sensitivities of the configuration with respect to changes in the user parameters.
• 08/29/2024 The Engineering Sketch PadJohn F. Dannenhoffer, III, Syracuse UniversityThis seminar will present the Engineering Sketch Pad (ESP), a geometry creation and manipulation system whose goal is to support the analysis methods used during the design process.
• 08/22/2024 Fluid-Structure Interaction Simulations of​ Supersonic Parachute InflationFrançois Cadieux, Computational Aerosciences Branch, NASA Ames Research CenterThis talk will discuss the Launch, Ascent, and Vehicle Aerodynamics (LAVA) teams recent work developing the capability to simulate supersonic parachute inflation.
• 08/13/2024 High Order Entropy Stable Discontinuous Galerkin DiscretizationsJesse Chan, Rice UniversityThis talk will review the construction of robust entropy stable discontinuous Galerkin methods, as well as extensions of entropy stable formulations to positivity preserving schemes.
• 07/11/2024 Partially-Averaged Navier-Stokes Approach for Unsteady Separated FlowsAndrea Petrocchi and George Barakos, University of GlasgowThis presentation introduces a bridging model between RANS and DNS, called Partially-Averaged Navier-Stokes (PANS), able to switch seamlessly between the two and obtain intermediate resolution.
• 07/02/2024 An Update on VTK, ParaView and TrameSebastien Jourdain, Kitware Inc.This talk will focus on the recent advancements in VTK and ParaView covering performance, rendering, in-situ and what we are working on to future proof our platforms. Then we’ll introduce trame, and how it empowers VTK and ParaView to be used by a wider set of users.
• 06/27/2024 Fourier Pseudo-Spectral Algorithms for Turbulence on Leadership-Class GPU PlatformsP.K. Yeung, Georgia Institute of Technology and Kiran Ravikumar, Science and Technology Corporation / NASA Ames Research CenterThis talk will discuss how different machine-specific programming models have allowed us to extract maximum benefit from two successive top-ranked GPU platforms, namely Summit and Frontier, at the Oak Ridge Leadership Computing Facility (OLCF).
• 06/13/2024 LAMMPS and SPARTA: Performance Portability Through KokkosStan Moore, Sandia National LaboratoriesThis presentation will discuss how the LAMMPS molecular dynamics code and the SPARTA direct simulation Monte Carlo code have been ported to use Kokkos performance portability abstractions.
• 06/06/2024 On the Importance of Accurate Simulation of Attached Boundary Layers in the Frame of Hybrid RANS/LES & WMLESSébastien Deck & Nicolas Renard, ONERACFD is playing an ever-expanding role in aerospace and enhancing its capabilities to predict unsteady turbulent flows is considered as a major objective to the field. This seminar will revolve around the major question of the treatment of attached boundary layers in the frame of high Reynolds number applications.
• 05/30/2024 Development of an Automated Volume Mesh Generation CFD Framework for Hypersonic Heat Flux PredictionsJoel A. McQuaid, University of Maryland, College ParkThis seminar outlines the creation of the overset CHAMPS near body solver (NBS) and Cartesian-AMR solver framework, called the NBS-Cart solver, and is designed for automatic volume mesh generation. This new approach has been tested over a wide range of hypersonic heating scenarios and fluid-ablation interaction cases.
• 05/23/2024 Revolutionizing Gas Turbine TestingShoreh Hajiloo, GE Power and David Egan, Ennova Technologies, Inc.This seminar will discuss a new approach for developing reliable CAD meshes using Ennova with a novel topology-based meshing method, rather than a shrink-wrap method normally used for large models.
• 05/16/2024 On Modal Methods for the Study of Transonic Buffet on WingsSebastian Timme, University of LiverpoolThis talk will discuss operator-based (global stability and resolvent) methods in the study of transonic edge-of-the-envelope wing aerodynamics.
• 05/09/2024 Slip-Wall-Modeled Large-Eddy Simulation for the Prediction of Smooth-Body SeparationMichael Whitmore, Stanford UniversityThis seminar will discuss a slip wall model application as an alternative formulation to predict high Reynolds number boundary layers in wall-modeled large-eddy simulations using a variety of geometries.
• 04/25/2024 Making Codes Performance Portable Without Using C++ AbstractionAnshu Dubey, Argonne National LaboratoryA new methodology and a set of tools has been created that can help non-C++ codes retain portability, and also help C++ codes do so without depending on template meta-programming.This presentation will describe the tools and methodology, and also describe how they are used to convert FLASH, usable on CPU only platforms, to Flash-X which is used on a variety of platforms, and in multiple science domains.
• 04/18/2024 Numerical Modeling of High-Pressure Multi-phase Multi-species FlowsNguyen Ly, Stanford UniversityThis talk will present the recent development of the Regularized-Interface Method (RIM) as a unified formulation that can describe both sub- and supercritical processes as well as the transition between them.
• 04/11/2024 Kokkos in SPARC: Performance Portability Experiences in a CFD ApplicationTravis Fisher, Sandia National LaboratoriesThe Sandia Parallel Aerodynamics & Reentry Code (SPARC) application is one of Sandia National Laboratories’ exascale demonstration applications. This talk will demonstrate SPARC’s performance portability on CPU only, CPU+threads, and CPU+GPU systems for a representative problem and highlight how SPARC achieves performance portability using Kokkos and performance portable linear solvers available in Trilinos.
• 04/04/2024 Kokkos: Performance Portability for the Exascale EraChristian Trott, Sandia National LaboratoriesThis talk will provide an overview of Kokkos, a unified programming model which can target a variety of architectures, and explain why one might want to leverage it and discuss its future directions.
• 03/28/2024 High-Fidelity Simulations of Multiphase FlowsSuhas Jain, Georgia Institute of TechnologyMultiphase flows are ubiquitous in nature and engineering processes. However, there are various challenges in the numerical modeling of multiphase flows. This talk will highlight these challenges and present a novel diffuse-interface model and numerical methods for robust simulations of incompressible and compressible multiphase flows.
• 03/21/2024 Predictive LES of Aircraft Icing AerodynamicsBrett Bornhoft, Center for Turbulence Research, Stanford UniversityEncouraged by recent studies using LES that demonstrate the ability to predict stall characteristics on full aircraft with smooth wings at an affordable cost, this study seeks to apply this methodology to icing conditions.
• 03/14/2024 Trailing-Edge Noise and its Applications to Urban Air Mobility NoiseSeongkyu Lee, University of California, DavisThis seminar will discuss the underlying physical mechanisms of the generation of trailing-edge noise using high-fidelity numerical simulations. Recent progress in both predicting and mitigating this noise will also be highlighted.
• 03/07/2024 Introducing Tecplot 360’s New Data Architecture to Improve UX with Transient Datasets & Design ExplorationScott Fowler, Tecplot, Inc.This talk will describe work that Tecplot, Inc. has underway to improve the usability and efficiency of Tecplot 360, particularly for transient datasets. Tecplot will introduce three new concepts that will be used in future versions of Tecplot 360: Data Journal, Deferred Data Options, and Parts.
• 02/29/2024 Is Thrust Well Defined?Mark Drela, Massachusetts Institute of TechnologyIn the presentation, the validity and rigor of thrust-drag decomposition will be examined, and several existing thrust and drag calculation methods will also be examined and evaluated. Distinctions will be made between rigorous thrust and drag definitions, evaluation approximations, and correlation-based estimates.
• 02/22/2024 Shaping Sustainable Flight with Design OptimizationJoaquim Martins, University of MichiganThis talk will examine the latest developments in CFD-based design optimization, addressing the critical challenges in shaping aircraft for enhanced efficiency and reduced emissions.
• 02/15/2024 Propulsor Behavior Under the Highly Distorted Flow of Boundary Layer IngestionGregory Heinlein, NASA Glenn Research CenterThis seminar will discuss a code-coupling approach with the LAVA computational framework and the TURBO code to capture the nature of the closely coupled nature of aircraft engine propulsors operating with boundary layer ingestion.
• 02/08/2024 PYCNIC: A Machine Learning Approach for Detecting Convergence of CFD SimulationsJoshua Diaz, Science and Technology Corporation, NASA Ames Research CenterThis seminar will discuss a supervised deep learning approach, coupled with heuristic convergence criteria, to construct a classification model for detecting the completion (convergence) of computational fluid dynamics simulations.
• 02/01/2024 Predicting Transonic Buffet Onset for the Boeing SUGAR Mach 0.8 Transonic Truss-Braced Wing AircraftOliver Browne, Science and Technology Corporation, NASA Ames Research CenterThis seminar will discuss flow past the Boeing Transonic Truss-Braced Wing aircraft, simulated with a Hybrid Reynolds-Averaged Navier-Stokes Large-Eddy Simulations turbulence modeling approach, to study transonic buffet onset and evaluate the predictive capability of the numerical approach.
• 01/25/2024 Statistically Consistent Dispersion of Line Loads to Uncertain Integrated Forces and MomentsAaron Burkhead, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will describe a method to characterize uncertainty on launch vehicle "line loads" that is consistent with uncertainty in the integrated loads, even if the line loads come from CFD and the integrated loads come from wind tunnel tests.
• 12/14/2023 Step Truncation Methods for Nonlinear Evolution Equations on Tensor ManifoldsAbram Rodgers, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will present new adaptive algorithms for temporal integration of nonlinear evolution equations on tensor manifolds. These algorithms, which we call step-truncation methods, are based on performing one time step with a conventional time-stepping scheme, followed by a truncation operation onto a tensor manifold.
• 12/07/2023 Towards Efficient and Reliable Model Reduction of Many-Query CFD ProblemsMasayuki Yano, University of Toronto Institute for Aerospace StudiesMany engineering tasks, such as optimization, uncertainty quantification, and optimal control, require CFD simulation for many different configurations and/or in real time. This talk will consider projection-based model reduction of parametrized CFD problems to accelerate the solution of many-query/real-time problems by several orders of magnitude, while providing error estimates in predictive settings.
• 11/30/2023 Rapid Analysis and Management of Large Spatiotemporal DataBen O’Neill, RNET Technologies and Rohit Deshmukh, Florida Atlantic UniversityThis talk will introduce a lossy reduce-then-analyze strategy that enables efficient data storage, transfer, and analysis. This data reduction method, called the Data-informed Local Subspaces (DLS), uses data-driven feature learning and data-enriched finite element methods to transform high fidelity data into a reduced format that promotes rapid data analytics.
• 11/02/2023 Discretization-Consistent LES Closure StrategiesAndrea Beck, University of StuttgartThis talk will discuss how to find optimal, discretization-specific LES closure strategies. For this purpose, the task is formulated as a Markov decision process and solved by Reinforcement Learning (RL). This allows to adjust the model to the actual discretization as it also incorporates the interaction between the discretization and the model itself.
• 10/12/2023 Panel Methods: Relevant in the 21st Century?Vivek Ahuja, Research in FlightPanel methods have traditionally aimed to strike the perfect balance between traditional CFD methods and simpler methods like lifting-line and vortex lattice methods. This seminar explores these ideas in the context of the work accomplished by Vivek Ahuja and the team at Research in Flight as part of their ongoing NASA and U.S. Air Force tool-development activities.
• 10/05/2023 Advances in Resolvent-Based Modeling of Turbulent FlowsAaron Towne, University of MichiganThis seminar will discuss two efforts to extend resolvant analysis beyond its limitations: a new computational algorithm to enable analysis of large-scale systems that overcomes the main computational bottlenecks, and a novel resolvant-based flow estimation and control framework.
• 09/21/2023 A Study on Flow Solutions Computed on Automatically and Manually Generated Structured Overset MeshesAndrew M. Chuen and William M. Chan, NASA Ames Research CenterThis seminar will cover a recently developed scheme at NASA's Ames Research Center that enables automation of structured overset surface mesh generation, a process that typically requires extensive user expertise and effort.
• 09/14/2023 PDE-based Methods for Multiscale Computational Fluid DynamicsRaaghav Ramani, University of California, DavisThis talk will present a new numerical framework for simulating fluid flows in multiple space dimensions, and an associated set of algorithms that are high-order accurate, flexible and applicable to a variety of flow configurations, highly efficient, and simple to implement.
• 09/07/2023 NVIDIA Developments for CFD Applications on GPUs and Arm CPUsStan Posey and John Linford, NVIDIAThis talk will examine some of the latest CFD implementations for GPUs with examples from commercial and research application software, as well introduce a new data center system design for power-efficient HPC based on the NVIDIA Grace Arm CPU and latest H100 GPU.
• 08/31/2023 On the Relevance of Atmospheric Particles for Laminar-Turbulent Transition in Hypersonic FlightChristoph Brehm, University of MarylandThis presentation explores the relevance of atmospheric particles on hypersonic transition in free flight. The presentation gives an overview of all relevant aspects that need to be considered to determine whether atmospheric particles can cause transition to turbulence in free flight.
• 08/24/2023 3D Virtual Simulation System of CoFlow Jet Airfoil with Embedded Micro-Compressor ActuatorGecheng Zha, University of MiamiTo benefit practical aircraft systems with active flow control (AFC), it is essential to accurately simulate the AFC effectiveness, power required, energy conversion efficiency, and control law. This seminar will present a 3D virtual simulation system of CoFlow Jet AFC to achieve this purpose.
• 08/17/2023 Unsupervised Mesh Optimization for Improved Numerical Stability of Finite Volume MethodsMohammad Zandsalimy, University of British ColumbiaThis seminar will discuss novel methods to enhance the efficiency of a CFD stability improvement approach based on mesh modification, with improved vertex selection methodology to ensure fast and reliable optimization.
• 08/03/2023 Simulation of Shockwave/Turbulent Boundary-Layer Interaction Over an Elastic Panel with a Discontinuous Galerkin SolverMin Gao, Institute of Aerodynamics and Gas Dynamics, University of Stuttgart, GermanyThis seminar discusses a loosely-coupled high-order fluid-structure interaction (FSI) framework developed in order to investigate the influence of an elastic panel response on shock-wave/turbulent boundary-layer interaction (SWTBLI). Specifically, a split-form arbitrary Lagrangian-Eulerian discontinuous Galerkin spectral element method is employed in the fluid solver and a Legendre spectral finite element method in the structure solver.
• 07/27/2023 Recent Enhancements to Modeling Sonic Boom Propagation using Augmented Burgers’ EquationSriram Rallabhandi, Computational Aerosciences Branch, NASA Ames Research CenterSonic boom propagation through the atmosphere is modeled with an augmented Burgers’ equation which includes nonlinearity and loss mechanisms. This seminar details updated discretizations of the governing equations which are fully conservative and duality preserving.
• 07/20/2023 Aerodynamic Shape Optimization of Heat ExchangersJoshua Anibal, Science and Technology Corporation / NASA Ames Research CenterCurrent design methodology for heat exchangers remains rooted in analytical methods informed by empirical studies on simple geometries. Numerical optimization offers an alternative by using optimization algorithms and physics-based simulation to search the vast design space. This seminar will discuss applied adjoint-based shape optimization techniques to the design of heat exchangers for two example problems.
• 07/13/2023 The Role of Unconventional Aircraft Configurations in the Path to Net ZeroDavid Zingg, University of Toronto Institute for Aerospace StudiesIn order to eliminate its net emissions of carbon dioxide, aviation will have to move quickly away from kerosene to potentially sustainable alternative fuels such as biofuels and hydrogen. This presentation will describe some recent research toward technologies for achieving this goal, with emphasis on unconventional aircraft configurations that have the potential to offer improved energy efficiency relative the the dominant conventional tube and wing configuration.
• 07/06/2023 Anisotropic Mach Cone Aligned Mesh Adaptation for Low Boom SimulationsChase Ashby, NASA Ames Research CenterAn automated, off-body Mach cone aligned structured curvilinear grid generation procedure is presented for near-field computational fluid dynamics simulations. Automation is achieved through a novel direction-based adaptation indicator formulation. The adaptation procedure is demonstrated on the JAXA Wing Body geometry and X-59 C608 demonstrator model from the Second and Third AIAA Sonic Boom Prediction Workshops, respectively.
• 06/29/2023 Sliding Mesh Applications Using the LAVA Curvilinear SolverErcan Dumlupinar and Luis S. Fernandes, NASA Ames Research CenterDynamic overset meshing, commonly used for simulations involving rigid body motion, can be computationally demanding due to the frequent requirement of hole-cutting and updating connectivity between different parts of the grid system. These operations can significantly increase the computational cost of such simulations. This work investigates the aerodynamic and aeroacoustic behavior of the Source Diagnostic Test (SDT) fan, as well as the Contra-Rotating Open Rotor (CROR) system, with the goal to conduct these analyses efficiently and in a manner that allows for detailed parametric studies.
• 06/22/2023 On Simulating Bird, Ice and Other Structural Impacts, Penetrations & Material Failure ModelingIan Do and Craig Miller, ANSYS, Inc.This presentation will discuss a wide range of impact dynamic simulations using a variety of advanced methods under a single suite code ANSYS-LS-DYNA, with emphasis on impacts of aerospace structures, including bird strike, jet engine containment, water landing, ice impact & material failure.
• 06/20/2023 100X: Leveraging the Future Potential of US Exascale Computing Project InvestmentsMichael A. Heroux, Sandia National LaboratoriesThis seminar will provide a summary of the US Department of Energy's Exascale Computing Project, which produced dozens of GPU-enabled, scalable application codes and dozens of GPU-capable libraries and toos that underpin these applications.
• 06/08/2023 Development of Reverse Monte Carlo Ray Tracing to Solve Radiative Heat Transfer in Fibrous MaterialsAhmed H. Yassin, University of KentuckyThis seminar will introduce an in-house reverse Monte Carlo ray tracing radiative heat transfer solver that has low statistical errors, reduced development time and computational cost, and includes the modeling of anisotropic and heterogenous media.
• 06/01/2023 High-Fidelity Numerical Simulations of Hypersonic High-Enthalpy FlowsDonatella Passiatore, Stanford UniversityThis seminar will investigate multiple turbulent, wall-bounded configurations of high-enthalpy flows, with the aim of studying the effect of finite-rate chemistry and vibrational relaxation on highly compressible turbluent flows.
• 05/25/2023 Applications of Flow Control to a Commercial AircraftArvin Shmilovich, Boeing Research and Technology; and Paul Vijgen, Boeing Commercial Aircraft (Retired)This presentation will cover selected material from the three papers presented by Boeing at the 2023 AIAA SciTech conference, summarizing the NASA funded Localized AFC (Active Flow Control) project. The presentation is dedicated to the memory of Dr. John C. Lin of NASA who initiated this project.
• 05/23/2023 To Mars! Machine Learning with Supersonic Retropropulsion Wind Tunnel Test DataMatthias Ihme, Stanford UniversityThis presentation explores machine-learning methods to advance the fundamental understanding of multi-nozzle plume physics, to quantify uncertainties, and to inform deployment of supersonic retropropulsion (SRP) technology.
• 05/11/2023 A Variational Theory of Aero-HydrodynamicsHaithem Taha, University of California, IrvineThis talk will present a special variational principle revived from the history of analytical mechanics: Hertz’ principle of least curvature. Using this principle, we developed a novel variational formulation of Euler’s dynamics of ideal fluids that is fundamentally different from the previously developed variational formulations based on Hamilton’s principle of least action.
• 05/04/2023 Adaptive Mesh Refinement Disturbance Flow Tracking Applied to Hypersonic Boundary Layer Transition PredictionVincenzo Russo, University of KentuckyThis presentation will detail the Adaptive Mesh Refinement Wave-Packet Tracking method and its application to a wide range of boundary layer transition problems, including particle-induced transition, transition on a finned cone and BOLT.
• 04/27/2023 Multi-Fidelity Modeling Under UncertaintyRamin Bostanabad, University of California, IrvineDesign of many engineered systems such as advanced materials relies on solving complex optimization problems. This complexity stems from multiple sources such as lack of high-fidelity experimental data, inaccuracy and bias of simulations (due to, e.g., missing physics), high cost of data acquisition, and existence of categorical variables that give rise to combinatorially expanding design spaces. This seminar will propose a multi-fidelity Bayesian optimization framework for designing materials composition under uncertainty.
• 04/20/2023 Big Data Analytics for Decision MakingValerio Pascucci, University of UtahThis talk will present computation tools and approaches that permeate the software stack and all stages of workflows, dealing with many of the major impediments. Examples from neuroscience, materials science, wildfire management, and natural language processing show how key innovations at all stages of the workflows help reduce the time to discovery and produce new insights.
• 04/06/2023 Wall Modeled LES: Recent Experience in Nonequilibrium Flows and Thoughts on its ConvergenceGeorge Ilhwan Park, University of PennsylvaniaThis talk will summarize research on wall-modelled LES conducted with the primary goal of assessing state-of-the-art wall models in controlled nonequilibrium flows and producing a better understanding of the notion of convergence in inherently under-resolved wall-modeled LES calculations.
• 03/28/2023 How Cloud Computing, Machine Learning and High-Performance Computing (HPC) are Accelerating the Adoption of HRLES and WMLES Methods for IndustryNeil Ashton, Amazon Web ServicesThis seminar will focus on how cloud computing, machine learning, and HPC are converging together to significantly accelerate the adoption of HRLES and WMLES CFD methods for industry, as well as bring disruptive technologies such as machine learning closer.
• 03/16/2023 Assessment of Trailing-Edge Surface-Normal Active Flow Control for Lift Enhancement on High-Lift SystemsSheida Hosseini & James Koch, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will discuss the application of microjets as an Active Flow Control technology to control circulation and thereby enhance high-lift performance. Various 2D and 3D computational and expermental studies will be showcased.
• 03/09/2023 CAPE: NASA Software for Large CFD Run MatricesDerek Dalle, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will coincide with the official version 1.0.0 version of CAPE. Derek is the primary developer and originator of CAPE will highlight some of the advantages of a tool like CAPE, how much work it might require for users to begin using CAPE, and the known limitations of the current CAPE package.
• 02/28/2023 Vision of oneAPI: Innovation through Abstraction James Reinders and Vasanth Tovinkere, Intel CorporationTwo senior Intel engineers from the oneAPI project will provide an overview of the vision of oneAPI and how it is architected to support diverse hardware that goes a long way in allowing software innovation to fully exploit the underlying system regardless of vendor or architecture.
• 02/21/2023 Axial Compressor Rotors – Conceptual Aerodynamic Design and Reverse EngineeringRalph Peter Mueller, CFturbo, Inc.This talk will present the latest CFturbo approach to designing Turbomachinery components in two different ways. At first, from the ground up, and the second based on a unique reverse engineering technique transforming existing neutral format 3D-CAD models to parametric Turbomachinery components.
• 02/09/2023 Parallel Mesh Adaptation for Unsteady Blast Simulations on Cartesian MeshesWade Spurlock, NASA Ames Research CenterMesh adaptation is essential for controlling the cost of large-scale, high-resolution simulations. We propose an efficient parallel unsteady adaptation approach that uses multiple sweeps over the time domain. The simulation is divided into a set of temporal “windows”each having a spatial mesh and time step adapted for a fraction of the total solution time.
• 02/02/2023 Enabling Supersonic Over-Land Flight Using Computational ModelingScott Neuhoff, NASA Ames Research CenterThis talk will present new developments in the Launch Ascent and Vehicle Aerodynamics (LAVA) CFD solver framework which are tailored to the analysis of supersonic vehicles, like the Quesst Mission's X-59 aircraft concept, and sonic boom propagation.
• 12/20/2022 Broadband Reconstruction of Inhomogeneous Turbulence Using a Combination of Data and Physics Driven ModelingAditya Ghate, NASA Ames Research CenterThis talk will present a new methodology to construct three-dimensional, temporally stationary but spatially inhomogeneous, incompressible turbulence.
• 12/08/2022 Bayesian Machine Learning for Data-Enhanced CFDPaola Cinnella, Sorbonne UniversityThis seminar will discuss a wall/SGS model for large-eddy simulations using the flow as a collection of building blocks that enables wall stress prediction.
• 11/10/2022 Building-Block Flow Model for Large-Eddy SimulationAdrian Lozano-Duran, MITThis talk will discuss Bayesian machine learning, a framewrk well-suitied for scarce or noisy data since it enables simultaneous models selection and inference, and provides estimates of uncertainty in model outputs.
• 11/1/2022 “All-Clear” Prediction of Solar Energetic Particle Events with Machine LearningViacheslav M. Sadykov, Georgia State UniversityThis seminar will cover work aimed at predicting Solar Energetic Particle events, supporting NASA's Early Stage Innovation Program.
• 10/25/2022 Synthesizing Turbulent Channel Flow: A Proposed Form of Solution to Steady Turbulence in ChannelsJohn William Poduska, Weston, MAThis seminar will discuss the Gaussian Transform (GXF), a formal representation of the random velocities of turbulent flows using a few ordinary, smooth, non-random functions with an ordinary Stochastic Intergral.
• 10/20/2022 Efficient and Robust Spectral-Element Methods on Triangles Using Tensor-Product Summation-by-Parts OperatorsTristan Montoya, The University of TorontoThis presenation will discuss conflicting objectives in summation-by-parts methods, which are reconciled by using separable polynomial expansions and tensor-product quadrature rules in collapsed coordinates to construct nodal as well as modal spectral-element discretizations on triangles which possess a tensorial operator structure in addition to the SBP property.
• 10/13/2022 Validation of a Fully Coupled Fluid-Ablation Interaction Solver for Low and High Temperature Ablators Alex Zibitsker, The University of KentuckyThis talk will present the coupling of the CHAMPS near body-Cartesian solver and the KATS material response solver, which is validated for low and high temperature ablators at hypersonic speeds. The CHAMPS near body-Cartesian solver is a fully automatic CFD code capable of employing adaptive mesh refinement for shock tracking and moving boundary problems while a near body grid is used to resolve boundary layer gradients for accurate and efficient heat flux predictions.
• 10/04/2022 Turning Noise into Data: Characterization of the Van Allen Radiation Belt Using SDO Spikes DataSpysos Kasapis, University of MichiganThis seminar will discuss a correlation study between SDO/AIA data and radiation belt activity within SDO's orbit. By extracting radiation “spike” data from the SDO/AIA images, we produce a comprehensive data product which is correlated not only with geomagnetic parameters, but also with the electron and proton fluxes measured by the GOES-14 satellite.
• 09/29/2022 CFD Methods for Aircraft Icing AnalysisIsik Ozcer, ANSYS Inc.In this webinar, Ansys' CFD approach to in-flight icing simulation will be described with highlights on some key physics that influence the ice accretion process. A brief description of the icing process for airframes and engines will be presented, followed by modeling approaches and examples.
• 08/30/2022 Predictions of LAGOON Nose Landing Gear Aeroacoustics using Wall-Modeled Large Eddy SimulationsMan-Long Wong, Science and Technology Corporation, NASA Ames Research CenterThis presentation will cover wall-modeled large-eddy simulations of the LAGOON nose landing gear using the Launch Ascent and Vehicle Aerodynamics (LAVA) framework.
• 08/25/2022 Validation of Actuator Disk, Actuator Line and Sliding Mesh Methods within the Structured Curvilinear Overset SolverGerrit-Daniel Stich, Science and Technology Corporation, NASA Ames Research CenterThis presentation will discuss a study being conducted using the LAVA flow solver to assess propulsion models with various fidelities, using the actuator-disk, actuator-line, and sliding-mesh methodologies.
• 08/18/2022 Combustion Machine Learning: Principles, Progress, and PerspectivesMatthias Ihme, Stanford UniversityThis presentation examines machine learning (ML) techniques for applications in combustion science and engineering. Starting with a review of sources of data, data-driven techniques, and concepts, we discuss supervised, unsupervised, and semi-supervised ML methods. Challenges unique to combustion ML are discussed and further opportunities are identified, focusing on interpretability, uncertainty quantification, the need for community-driven benchmark data, and the augmentation of ML methods with prior combustion-domain knowledge.
• 08/11/2022 Improved CFD Methodology and Workflow Using Solution-Based Adaption in Ansys FluentAdam Norman, ANSYS Inc.This webinar will present a methodology that obviates the problem of over-refinement without compromising the accuracy of the CFD solution, with an overall result of an improved design process. A Hessian-based adaption criteria is used to capture the important flow features starting from a relatively coarse and non-finely tuned mesh of an external flow calculation.
• 08/09/2022 Meshless Large Eddy Simulation of Multirotor Aircraft through the Reformulated Vortex Particle MethodEduardo J. Alvarez, Brigham Young UniversityThis seminar presents a novel computational fluid dynamics scheme based on a reformulated vortex particle method (rVPM) for the analysis of complex interactional aerodynamics. The rVPM is a meshless large eddy simulation solving the Navier-Stokes equations in their vorticity form.
• 08/02/2022 Navier-Stokes Equations: Reliability, UQ, and Extension for Strong Nonequilibrium FlowsNarendra Singh, Stanford UniversityThis seminar will present the development of a rigorous metric to assess the breakdown of Navier-Stokes equations starting from kinetic theory. New Hybrid methods are discussed, which can combine continuum description using Navier-Stokes equations and microscopic description to produce efficient high-fidelity numerical simulations.
• 07/21/2022 Algorithmic Improvements to a High-Order Space Marching Method for Sonic Boom PropagationJeffrey A. Housman, Computational Aerosciences Branch, NASA Ames Research CenterAlgorithmic improvements to a high-order space marching method enabling an efficient strategy for sonic boom propagation by coupling near-field Computational Fluid Dynamics (CFD) solutions to an efficient space marching solver are described. The space marching solver is based on a high-order accurate finite-difference discretization of the 3D Euler equations on a specially designed curvilinear grid to enable a single sweep space marching solution.
• 07/07/2022 Novel Sub-filter Closures for Compressible FlowsVictor Sousa, Purdue UniversityThis talk will present a new perspective on closures for filtered governing equations that allow for a unified framework for shock capturing and sub-filter turbulence modeling, as well as an extension to discontinuous flux reconstruction methods with a focus on shock-dominated flows.
• 06/23/2022 Ansys Fluent High-Speed Combustion/Reacting Flow ModelingBruce Crawford, Ansys, Inc.In this talk, workflows will be shown utilizing the latest improvements and features in Ansys Fluent to model air breathing engines (for example, ramjets, scramjets, RDEs), re-entry chemistry, and liquid/solid rocket motors. The speaker will be walking through specific, targeted examples on how Ansys Fluent is solving some of the most complex systems problems.
• 06/16/2022 Inferring the Sources Driving Variations in Atmospheric Composition at the Urban Scale using Dense Observational NetworksAlex Turner, Department of Atmospheric Sciences, University of Washington, SeattleThis talk will discuss recent work to characterize atmospheric composition at the urban scale and the processes driving fine-scale variations using models and dense observational networks. We will use in situ measurements from a dense urban monitoring network to investigate the impact of mobility restrictions in response to COVID-19 on urban CO2 emissions.
• 06/09/2022 Predicting High-Lift Aerodynamics on NASA Common Research Model - Part III: Wall Modeled Large Eddy SimulationsAditya Ghate, Science and Technology Corp./NASA Ames Research CenterThis seminar will present a new immersed boundary Wall-Modeled Large Eddy Simulation (WMLES) formation developed to study high-lift aerodynamics on the NASA High-Lift Common Research Model. Based on the findings of the grid refinement study a new coarser “best-practice” grid utilizing targeted refinement is constructed.
• 06/02/2022 Predicting High-Lift Aerodynamics on NASA Common Research Model - Part II: Delayed Detached Eddy SimulationsOliver Browne, Science and Technology Corp./NASA Ames Research CenterThis seminar will present an assessment of a hybrid Reynolds Averaged Navier-Stokes Large Eddy Simulations approach for CLmax prediction using the Launch Ascent and Vehicle Aerodynamics solver.
• 05/26/2022 Predicting High-Lift Aerodynamics on NASA Common Research Model - Part I: Reynolds Averaged Navier-Stokes SimulationsJared Duensing, NASA Ames Research CenterThis seminar will provide an in-depth assessment of the High Lift Common Research Model (CRM-HL) aerodynamic performance using a Reynolds-Averaged Navier-Stokes (RANS) methodology within the Launch, Ascent, and Vehicle Aerodynamics (LAVA) framework.
• 05/19/2022 NASA Langley Low-Speed CFD Contributions to the Space Launch System ProgramBrent Pomeroy, NASA Langley Research CenterIn this presentation, low-speed computational work from NASA Langley in support of the Space Launch System (SLS) is discussed. This information will include both historic and present efforts with Kestrel, FUN3D, and USM3D.
• 05/05/2022 Space Launch System (SLS) Base Convective EnvironmentsManish Mehta, NASA Marshall Space Flight CenterThis presentation will discuss the various trends of the base convective and pressure environments within the SLS core-stage and booster base regions.
• 04/28/2022 Wind-tunnel, Static Burn and Flight Tests Conducted to Establish the Aeroacoustics Environment of Orion Multi-Purpose Crew Vehicle (MPCV)Jayanta Panda, NASA Ames Research CenterThis presentation will summarize the pressure fluctuation tests used to develop and certify the initial shape of the MPCV during launch, and will discuss the progression of knowledge and databases for the project.
• 04/21/2022 Contributions of Engineering Risk Assessment to the Artemis ProgramScott Lawrence, NASA Ames Research CenterThe Engineering Risk Assessment (ERA) team at NASA Ames Research Center is responsible for providing estimates of abortability with respect to various failure modes of the Space Launch System (SLS). This talk will describe the role of this type of analysis as well as tools and processes that have been developed and applied to generate the abortability data.
• 04/14/2022 Development of NASA’s unsteady Pressure-Sensitive Paint Capability with the Space Launch System and High-Performance ComputingNettie Roozeboom, Experimental Aero-Physics Branch, NASA Ames Research CenterA new state-of-the-art technique to measure unsteady aerodynamics is currently being developed using pressure-sensitive paint (PSP), high-speed cameras, and advanced image processing methods. During a recent test campaign, a direct connection was established between the Unitary Plan Wind Tunnel and the NASA Advanced Supercomputing Division, allowing for rapid data transfer and near-real-time processing.
• 04/07/2022 Orion AerosciencesRyan McDaniel, Aerothermodynamics Branch, NASA Ames Research CenterThe design of the Orion spacecraft’s thermal protection system (TPS) is based largely on computational fluid dynamics (CFD) analyses. The computational tools, analysis methods, and key data products used to develop Orion’s aerothermal database will be presented.
• 03/31/2022 Advances in Launch Vehicle Ascent and Booster Separation CFDDerek Dalle & Jamie Meeroff, Computational Aerosciences Branch, NASA Ames Research CenterWith the imminent launch of Artemis I, this seminar will present highlights of the work done by the Ames SLS CFD Team, part of the Computational Aerosciences branch at NASA Ames, to support the Artemis program and specifically Space Launch System (SLS) over the last 8 years.
• 03/24/2022 Towards Multiphase Simulations of Launch Environments for Acoustic PredictionsJordan Angel, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will go over CFD modeling and simulation of the SLS launch environment, including the water-based sound suppression system used to dampen acoustic vibrations.
• 03/17/2022 Predicting Orion Launch Abort AcousticsFrançois Cadieux, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will discuss a campaign of CFD scale-resolving simulations undertaken by the Launch Ascent and Vehicle Aerodynamics (LAVA) team to analyze and predict vibrational loads on the Orion crew capsule during an abort scenario.
• 03/10/2022 Increasing Modeling Fidelity in the Assessment of Electric Aircraft for Regional and Urban Air MobilityMatthew Clarke, Stanford UniversityThis seminar will discuss both the necessity and methodology of incorporating medium-fidelity analytical techniques into the conceptual design stage of eVTOL aircraft for regional and urban air mobility.
• 03/03/2022 Development and Investigation of Accurate High-Order Generalized Summation-by-Parts Discretizations for Computational Fluid Dynamics David Craig Penner, University of TorontoThis seminar will discuss how to obtain accurate solutions and, particularly, superconvergent integral functionals when solving linear and nonlinear partial differential equations governing computational fluid dynamics problems of increasing practical relevance.
• 02/22/2022 Efficient Aircraft Flutter Analysis Using Model Order Reduction with Error EstimationBrandon Lowe, University of TorontoFlutter safety is an important consideration in the design and development of aircraft. However, fast and accurate flutter analysis in the transonic regime remains an open problem due to the high computational cost associated with accurately modeling transient aerodynamic forces. A model order reduction approach for flutter prediction with error estimation is presented. A projection-based model order reduction approach is used to create an aerodynamic ROM which is coupled to a structural model to create a primal aeroelastic ROM.
• 02/17/2022 Jet Noise Predictions with Wall-Modeled Large-Eddy SimulationsGerrit-Daniel Stich, Science and Technology Corporation / NASA Ames Research CenterNASA’s Commercial Supersonic Technology (CST) project has formulated a technical challenge to design a quiet low boom supersonic aircraft that meets Federal Aviation Authority’s (FAA) noise regulations. A campaign of wall-modeled large-eddy simulations (WMLES) has been performed with the Launch, Ascent, and Vehicle Aerodynamics (LAVA) computational fluid dynamics (CFD) software to predict jet noise for single-stream asymmetric round jets at several flow conditions. The simulations address the new Prediction Uncertainty Reduction (PUR) technical challenge within the context of NASA's CST project.
• 02/10/2022 Conceptual Design and Propulsion Airframe Integration Studies for the SUSAN Electrofan Aircraft Timothy Chau, Leonardo Machado, NASA Ames Research Center; Byung Joon Lee, NASA Glenn Research Center; and Michelle Lynde, NASA Langley Research CenterThe SUbsonic Single Aft eNgine (SUSAN) Electrofan is a new regional transport aircraft concept that uses a 20 Megawatt Electrified Aircraft Propulsion (EAP) system with advanced Propulsion-Airframe Integration (PAI) technologies to enable significant reductions in fuel burn and emissions. In this seminar, four research topics will be presented to showcase some of the modeling and simulation work being done by researchers at the NASA Ames, Glenn, and Langley Research Centers to support trade space explorations for the SUSAN Electrofan.
• 02/03/2022 Scale-Resolving Simulations of a Supersonic Retro-Propulsion Concept for Mars Entry, Descent, and LandingFrançois Cadieux, NASA Advanced Supercomputing DivisionAccurate and reliable CFD predictions are needed to help design future Mars entry, descent, and landing (EDL) vehicles due to the cost and limitations of wind tunnel tests. This work demonstrates how high-order scale-resolving simulations on Cartesian adaptive mesh refinement (AMR) grids can provide accurate and reliable time-averaged aerodynamic loads on the vehicle for this challenging flow regime.
• 01/27/2022 Recent Developments on Automation of Overset Structured Mesh GenerationWilliam Chan and Andrew Chuen, NASA Advanced Supercomputing DivisionA scheme is presented for the automatic generation of structured overset meshes on geometries that are defined by Boundary Representation (BRep) solids. A variety of test cases is presented including the Juncture Flow Experiment wing-body, a complex rotor hub for a hover experiment, the Multi-Rotor Test Bed, five rotorcraft concept vehicles, and various components of the High-Lift Common Research Model from the High-Lift Prediction Workshop 4 (HLPW4).
• 01/20/2022 Computational Analysis in Support of the Common Research Model Tail Cone Thruster Configuration Wind Tunnel TestLuis Fernandes, NASA Advanced Supercomputing DivisionThis seminar will discuss work utilizing the LAVA software being conducted as a precursor to an upcoming test campaign taking place in the National Transonic Facility for a CRM-based model with a retrofitted tail cone thruster.
• 01/13/2022 Modeling Particle-Laden Compressible Flows with Application to Plume-Surface InteractionsJesse Capecelatro, University of MichiganIn this talk, an Eulerian-Lagrangian framework for simulating gas-solid compressible flows under conditions relevant to PSI is presented. Simulations of underexpanded jets impinging on granular beds are performed to investigate the role of nozzle pressure ratio on crater morphology and particle ejecta.
• 12/09/2021 Aero-Structural Topology Optimization Framework for Transonic Aircraft Wingbox DesignPrateek Ranjan, University of Illinois at Urbana-ChampaignThis seminar will discuss research in the field of aircraft Multi-Disciplinary Design Optimization, with a focus on both low and high-fidelity numerical techniques for coupled aerodynamic shape and structural topology optimization. It will cover low-fidelity techniques for aero-elastic topology optimization, followed by a discussion of a large-scale aircraft MDO framework that aims to solve a PDE-constrained optimization problem at transonic speeds.
• 12/02/2021 A Computational Fluid-Structure Interaction Method for Simulating Supersonic Parachute InflationJonathan Boustani, NASA Advanced Supercomputing DivisionThis seminar will cover a new computational method that was developed to provide NASA with the capability to simulate supersonic parachute inflation. The method considers the loose coupling an immersed boundary method with a nonlinear finite element solver.
• 11/16/2021 The Harmonic Methodology for Unsteady Turbomachinery Modeling: Theory, Implementation and ApplicationsMateus Teixeira and Stephane Vilmin, Cadence Design Systems, Inc.This webinar will cover the fundamentals and applications of the harmonic methodology, which consists of solving turbomachinery models in frequency space, leading to a large savings in computational costs.
• 11/10/2021 Higher Fidelity Designs for the Aerospace Industry with Fluid-Thermal Structural InteractionSreedevi Krishnan, Ansys, Inc.This webinar introduces the physics coupling methodology and platform, while showcasing published validation studies relevant to aerospace applications. In addition, several case studies involving modeling of complex fluid-thermal and structural interaction in aerospace industry will be presented.
• 10/28/2021 SimplifyHPC: A Framework to Simplify HPC Codes DeploymentAnanta Tiwari, EP AnalyticsThis seminar will describe the SimplifyHPC framework and showcase its current capabilities with NASA's GEOS-Chem as a target application. It will demonstrate how SimplifyHPC can make managing this complex code seamless both on on-premises and on AWS clusters, all from a desktop application.
• 10/19/2021 Kombyne: Accelerated HPC Workflows via Production "In Transit"Steve M. Legensky, Intelligent LightThis seminar will introduce Intelligent Light's Kombyne software as a solution to the bottleneck created by writing, managing, and reading very large files. Kombyne seeks to simplify the integration of solver codes and minimize the runtime impact on memory and performance via "in transit" operation.
• 10/14/2021 An Examination of Quadcopter Drone Noise Using Computational AeroacousticsFranklyn J. Kelecy, Ansys, Inc.This talk will discuss how quadcopter drone noise can be examined using available aeroacoustic analysis methods in the general purpose CFD code Ansys Fluent. The objective is to estimate the overall sound pressure levels and spectral signatures at discrete positions beneath the drone, assuming a hovering flight condition.
• 10/07/2021 Aerodynamic Design Optimization of a Transonic Strut-Braced-Wing Regional AircraftTimothy Chau, Science and Technology Corporation, NASA Ames Research CenterThis presentation will cover attempts to address aerodynamic concerns at transonic speeds for a strut-braced-wing regional jet class aircraft.
• 09/29/2021 Effects of Counterflow Jet on the Performance of a Generic RocketSemih Olcmen, University of AlabamaThis seminar will discuss the effects of counterflow-jets on the drag of a generic missile shape at Mach numbers ranging from 4 to 9.
• 09/23/2021 Aerodynamic Separation of Fragmented Bodies in High-Speed FlowTom Whalen, University of MarylandMemComputing attempts to formalize the general concept of computing with and in memory, as opposed to conventional computing paradigms where the processing unit and memory are assumed physically separated entities exchanging information. This seminar introduces the Universal Memcomputing Machine (UMM) as the abstract model describing the class of non-von Neumann architectures leveraging the computational memory as central building block to study this alternative computing paradigm.
• 09/16/2021 Introduction to MemComputing and its Applications in High Performance ComputingFabio Lorenzo Traversa, MemComputing, Inc.MemComputing attempts to formalize the general concept of computing with and in memory, as opposed to conventional computing paradigms where the processing unit and memory are assumed physically separated entities exchanging information. This seminar introduces the Universal Memcomputing Machine (UMM) as the abstract model describing the class of non-von Neumann architectures leveraging the computational memory as central building block to study this alternative computing paradigm.
• 09/09/2021 Geometry-Sensitive, Solver-Independent Mesh Adaptation Using Hybrid Viscous and Hex-Core Meshing TechniquesNick Wyman and Travis Carrigan, Cadence Design Systems, Inc.This presentation will introduce a repeatable and user-independent approach to mesh generation using Pointwise by leveraging a goal-oriented framework coupled with hierarchical cartesian off-body meshing and adaptation.
• 09/02/2021 Morphing and Optimization with ANSA and META for Aerospace ApplicationsRavi Nimbalkar, BETA CAE Systems USAThe ability to set up parametric design changes on CAE models is a key enabler for a quick turnaround in the optimization process. This seminar will present morphing and optimization functionalities of the pre-processor ANSA and post-processor META as applied to typical aerospace models.
• 08/26/2021 Toward Aerodynamic Shape Optimization for the Design of Natural-Laminar-Flow WingsMichael Piotrowski, NASA Advanced Supercomputing DivisionThis seminar presents methods for the efficient prediction of boundary-layer transition in a RANS-based flow solver to accelerate the design of aircraft configurations using tools capable of incorporating and exploiting natural laminar flow. A new, smooth model is demonstrated to produce significantly improved numerical behavior and provides smooth gradients for the gradient-based optimization algorithm.
• 08/19/2021 Wall-Modeled Large-Eddy Simulation of High-Speed Turbulent Flows with an Immersed Boundary MethodWilliam van Noordt, the University of OxfordThis presentation introduces a coupled IBM-WMLES approach that is tailored to the simulation of high-speed turbulent flows. The basis of this method is to carefully address numerical dissipation and stability away from and close to the wall. This is achieved by using a hybrid central-upwind flux reconstruction scheme and careful application of smooth boundary conditions.
• 08/17/2021 Minimizing the Preprocessing Time Sink: A Guided, Fluent Meshing Workflow for the Aerospace and Defense IndustryVarun Chitta, Ansys, Inc.This presentation will provide an overview of the automated unstructured meshing workflow technology available with Ansys Fluent Meshing. Through live demonstrations, discover how engineers from the Aerospace and Defense industries can raise their efficiency with task-based workflows, Mosaic-enabled meshing technology, and a streamlined user interface to deliver more accurate results in less time.
• 08/12/2021 On a New Length Scale for the Buffer Zone of Turbulent FlowsSvetlana Poroseva, University of New MexicoWhen comparing model and DNS profiles for fifth-order velocity moments in a turbulent channel flow under the strain and in a turbulent boundary layer over a flat plate, small discrepancies were found in the buffer zone of both flows, with the stain in the channel flow improving the agreement between the model and DNS profiles. In this presentation, a new length scale will be introduced to improve the quality of relevant statistics collected from DNS near walls.
• 08/10/2021 Overset Moving Body 6-DOF Simulations using HPCMP CREATE A/V HeliosBeatrice Roget, Science and Technology Corporation / NASA Ames Research CenteThis presentation will describe new code development for the HPCMP CREATE-AV Helios framework to enable 6-DOF simulations of independently moving body systems, which can include configuration changes.
• 07/20/2021 AMD CPU Environment for HPJason Hogan-O’Neill, Advanced Micro Devices (AMD)AMD is leading the way into the Exascale era through its EPYC CPUs and Instinct GPU. In this presentation we briefly review the direction of travel AMD is taking for HPC; and then look in more detail at the third and current generation EPYC CPU, Milan, discussing its architecture and associated application characterization. Some discussion on the AMD Software Development Environment for the EPYC CPUs is included.
• 07/15/2021 CFD Helping to Mitigate COVID TransmissionFred Mendonca, OpenCFD LimitedThis seminar will discuss how CFD has been able to contribute to a wider understanding of airborne transmission, provide a real impact on prevention and mitigation, and how users can learn about virus behavior, interactions, and ventilation design. The challenge for CFD is to combine validated approaches to several underlying physics (turbulence, multi-species transport, thermodynamics, buoyancy, particle mass momentum, and heat transfer) into an ensemble of combined physics in enclosed spaces in order to be meaningful for CFD non-experts.
• 07/08/2021 Towards a Generalized Approach for Acoustically Adapted Synthetic Turbulence Generation at Zonal Hybrid RANS/LES InterfacesBalaji Muralidharan, CRAFT TechCombustion Research and Flow Technology (CRAFT Tech), in combination with NASA, is working on the development of an integrated, modular, well-validated software toolset for the generation of acoustically adapted synthetic turbulence to be used in conjunction with any zonal hybrid RANS/LES approaches. This software toolset is envisioned as a collection of STG approaches that are well-suited for integration with various CFD solvers that are widely used by NASA.
• 06/29/2021 Accelerate Your Discoveries in HPC & AI with AMDMike Schulte, Derek Bouius, Advanced Micro Devices (AMD)The era of exascale is here. Immense computational power coupled with the fusion of High-Performance Computing (HPC) and Artificial Intelligence (AI) are enabling researchers to tackle grand challenges once thought beyond reach. Disruptive technologies are needed to drive industries forward and AMD is at the center of this computing revolution. The AMD Instinct MI100 accelerator has been optimized for compute. It is built on AMD Infinity Architecture to deliver true heterogeneous compute capabilities for HPC and AI. Join Mike Schulte and Derek Bouius to learn how the AMD MI100 Instinct GPUs and AMD ROCm software ecosystem can propel your HPC and AI Deep Learning workloads.
• 06/24/2021 Vision for Next-Gen Modeling & Simulation for Aerospace Propulsion SystemsVenke Sankaran, AFRL Aerospace Systems Directorate, Edwards Air Force BaseDigital engineering represents a paradigm shift that will be critical for maintaining technological superiority. This seminar concerns the research and development for next-generation modeling and simulation tools to address the needs of this emerging digital enterprise. Key focus areas include: (1) development of multi-fidelity models for design and digital twins trained by high-fidelity models, and (2) data assimilation of experimental and operational data so that the models represent the authoritative source of truth. The talk will draw from several examples in aerospace propulsion for liquid and solid propellant combustion and plasma propulsion systems based upon research being conducted at the Aerospace Systems Directorate at AFRL. Specific focus will be on advanced physics-based model development for turbulent combustion and their systematic use for training and developing reduced-order models. The use of multi-scale and multi-fidelity models combined with data assimilation for design optimization and digital twins will also be discussed.
• 06/17/2021 On the Potential for High Throughput High Fidelity SimulationsSanjeeb Bose, Cascade TechnologiesIn this seminar, we revisit the potential for the use of LES in-design environments that require high throughput on two fronts. First, recent developments in numerical methods for unstructured grids, wall modeling for high Reynolds number flows, and mesh generation for complex geometries have reduced the computational cost for the prediction of salient quantities of interest in practical engineering flows. Second, we assess the computational cost impact due to the use of accelerated computing architectures (e.g., GPUs) both in terms of time and dollar costs using performance data collected from a variety of architectures. The synthesis of these data points suggest that we may be reaching a tipping point for more routine use of high-fidelity simulations in the engineering design process.
• 06/15/2021 High Fidelity Automated CFD Meshing for the Aerospace Sector Vangelis Skaperdas, BETA CAE SystemsThis webinar will demonstrate the meshing functionality of the pre-processor ANSA, as applied to typical aerospace models like the ones in the High Lift Prediction and Geometry and Mesh Generation workshops. We will address topics like geometry import and clean up; recognition of features such as sharp edges, leading edges, trailing edges, proximities etc.; setup of Size Fields to control mesh size distribution; setup of the batch mesh tool of ANSA for the automation of surface and volume meshing; and speed and memory usage for large CFD models.
• 06/10/2021 Large Eddy Simulation and Linear Analysis of an Airfoil in Transitional Flow: Insights on Secondary Tones and Acoustic Feedback William Wolf, University of CampinasA wall-resolved large eddy simulation is performed to study secondary tones generated by a NACA0012 airfoil at angle of attack = 3 deg. with freestream Mach number M = 0.3 and Reynolds number Re = 5x10^4. Laminar separation bubbles are observed over the suction side and near the trailing edge, on the pressure side. Flow visualization and spectral analysis are employed to investigate vortex shedding aft of the suction side separation bubble.
• 06/08/2021 Efficient Quantum Algorithm for Dissipative Nonlinear Differential Equations Hari Krovi, Raytheon BBN Technologies While there has been extensive previous work on efficient quantum algorithms for linear differential equations, analogous progress for nonlinear differential equations has been severely limited due to the linearity of quantum mechanics. Despite this obstacle, we develop a quantum algorithm for initial value problems described by dissipative quadratic n-dimensional ordinary differential equations.
• 06/03/2021 Three-dimensional Effects on Unsteady Dynamics and Turbulent Transport Mechanisms of an Impinging Shock Wave/Boundary-layer InteractionManan Vyas, NASA Glenn Research CenterIn this work, wall-resolved large-eddy simulation of an impinging shock wave/boundary-layer interactions, including the sidewalls, was performed based on the experiments performed at the Institut Universitaire des Systèmes Thermiques Industriel (IUSTI) for 8-degree wedge at Mach 2.29. The analysis identified unsteady dynamics of the reflected-shock foot, separation bubble, and corner region.
• 06/01/2021 Turbulence and Aeroacoustics in High-Speed Jets Sanjiva K. Lele, Stanford UniversityEngineering applications such as high-speed propulsion or supersonic/hypersonic aerodynamics require accurate predictions of compressible turbulent flows. To improve engineering models for these applications, it is helpful to separate variable-density or variable fluid property effects, which dominate the turbulence behavior in supersonic and hypersonic turbulent boundary layers from intrinsic compressibility effects associated with pressure-induced volume change.
• 05/27/2021 Numerical Noise Prediction and Source Identification of a Realistic Landing Gear Tulio Ricciardi, University of CampinasNoise predictions of a full-scale realistic landing gear from a widebody aircraft are obtained combining high-fidelity CFD simulations and the Ffowcs Williams and Hawkings (FWH) acoustic analogy. The aeroacoustic prediction of such a complex aeronautical system depends on geometry fidelity and the ability of the mesh and numerical method to resolve important flow features responsible for noise generation. To understand the role of small components in the far-field noise predictions, different setups are analyzed including a detailed full complexity landing gear and a simplified, yet realistic, configuration.
• 05/20/2021 C++ Parallel Algorithms for GPU Programming: A Case Study with the Lattice Boltzmann Method Jonas Latt, University of GenevaIn this presentation, the principles of C++ parallel algorithms are explained, and the simple case of the 2D heat equation is used to showcase the application of this formalism to numerical algorithms. An introduction to the STLBM, an open-source proof-of-principle implementation of Lattice Boltzmann (LB) algorithms for fluid flow, based on parallel algorithms will also be covered.
• 05/13/2021 Towards Scale-Resolving Simulations of Industrial Relevant Turbulent FlowsOriol Lehmkuhl, Barcelona Supercomputing CenterIn the last years, a significant effort has been done at the Barcelona Supercomputing Center to increase the technology-readiness level of Large Eddy Simulations by deploying low-dissipation strategies for the simulation of scale resolving turbulent flows into large scale applications. The talk will discuss the general strategy followed covering numerical methods, physical based sub-grid scale (SGS) closures, wall modeling, and High Performance Computing strategies.
• 05/04/2021 Thinking OpenMP with NVIDIA HPC CompilersGuray Ozen, NVIDIA CorpOpenMP is a directive-based programming model developed to solve productivity and performance as well as portability across target systems. In this talk, we will present NVIDIA's OpenMP target offload solution that provides performance portability across NVIDIA GPUs and multicore CPUs. We explain how to take advantage of our solution in C, C++, and Fortran using NVIDIA HPC compilers. We will also provide a list of concrete recommendations to programmers so that they, too, can obtain high performance on NVIDIA's GPUs. We will conclude our presentation by explaining interoperability among other models we implemented such as OpenACC, and standard language parallelism in C++ and Fortran.
• 04/29/2021 Fundamental Principles of the Discontinuous Galerkin Method and Extension to Multiphase Flow Problems Florian Kummer, Technical University of DarmstadtThe talk will be split into two parts: First, a general introduction into Discontinuous Galerkin (DG) methods will be given. The derivation of a DG scheme for a scalar convection equation will be demonstrated and implementation issues will be discussed. Then, an overview over the presenter’s personal contributions to the field will be given, mainly on the eXtended Discontinuous Galerkin (XDG) method for the simulation of incompressible two-phase flows. There, the fluid interface is tracked by a level-set method and the shape of the XDG basis functions is dynamically adapted to the position of the interface.
• 04/22/2021 Towards Industrial Large Eddy Simulation of Vortex Dominated Flow Using High-Order Methods Z. J. Wang, University of KansasThe promise of large eddy simulation (LES) has been known for many decades, and its application to real world flow problems, however, has been hindered by its computational cost. Although the Reynolds-averaged Navier-Stokes (RANS) approach has gained wide acceptance in industry, many applications call for LES. This talk will highlight efforts in improving the efficiency, accuracy and robustness of LES in high order space-discretization, efficient and scalable time integration, and GPU implementation.
• 04/15/2021 Model Order Reduction for Multidisciplinary Design Analysis and Optimization in Higher-Dimensional Parameter SpacesGabriele Boncoraglio, Stanford UniversityOptimization problems constrained by partial differential equations arise in many engineering applications, including design and optimal control. Even though the state of the numerical solution of PDEs has reached impressive levels of maturity, it remains a computationally intensive process. This talk introduces the method of active manifold as a superior alternative to the method of active subspace, whose capabilities are limited by the underlying affine approximation. It also presents an adaptive sampling approach that first predicts the region Dv ∁ D that will be visited by the optimization procedure using a low-cost approach, then trains the PROMs only in this region of the design parameter space.
• 04/08/2021 Adjoint Shape Optimization for Aerospace ApplicationsFranklyn J. Kelecy, Ansys, Inc.Adjoint-based optimization methods have seen increased use in Computational Fluid Dynamics (CFD) simulations as a means of providing sensitivity information for flow solutions and as the basis of shape optimization techniques for performance improvement and robust design. This presentation will provide an overview of the Ansys Fluent adjoint solver and its application to selected aerospace cases.
• 04/01/2021 Towards Predicting Transonic Aerodynamics using Wall Modeled Large Eddy SimulationsAditya Ghate, Science and Technology Corporation/NASA Advanced Supercomputing DivisionThis seminar will discuss wall-modeled Large Eddy Simulations (WMLES) of the NASA Common Research Model (CRM) performed at transonic conditions and various angles of attacks leading up to and including shock-induced flow separation. The LAVA WMLES simulations are shown to accurately predict the lift curve slope and the onset of separation characterized by the break in the pitching moment. Furthermore, careful assessment of skin-friction drag at cruise condition and its subsequent decrease with increasing angles of attack are shown to be in agreement with viscous sublayer resolving Reynolds Averaged Navier Stokes (RANS) simulations.
• 03/25/2021 Jet Noise Prediction for Chevron Nozzle Flows with Wall-Modeled Large-Eddy SimulationsGerrit-Daniel Stich, Science and Technology Corporation/NASA Advanced Supercomputing DivisionResults from ongoing research on jet noise prediction with wall-modeled large-eddy simulations (WMLES) performed with the LAVA computational framework were presented. In particular, the focus of this study is on mixing enhancements from a single stream chevron nozzle at Reynolds number of 1 million. Although the concept of chevron nozzles to reduce jet noise is not new, our understanding of its impact on the overall noise is still not well understood.
• 03/18/2021 Parametric Turbomachinery Design and Simulations: An Introduction to CFturboRalph Peter Mueller, CFturbo, Inc. & Metin Ozen, Ozen Engineering Inc.Turbomachinery design and fluid-flow simulations have reached new levels in turnaround time, robustness, and prediction accuracy in recent years. It became possible by combining high-fidelity CFD-solvers with optimization codes and parametric, knowledge-based conceptual design software. This talk will present CFturbo's fast and user-friendly approach to designing Turbomachinery components from the ground up, simulating performance curves, and getting optimized geometries using Ansys CFX and Ansys optiSlang. The showcase will be a cryogenic rocket turbopump.
• 03/11/2021 Turbulent Scaling Laws of Wall-Bounded Shear Flows for Arbitrary Moments, Their Symmetry Basis, and Its Validation Using DNS and Experimental DataMartin Oberlack, Technical University of Darmstadt, GermanyThis seminar will discuss work deriving turbulent scaling laws in wall-bounded shear flows for arbitrarily high moments of the flow velocity using the symmetry-based turbulence theory. The key ingredients are the symmetries of classical mechanics, especially the scaling of space and time, and two statistical symmetries, which are not directly observed in Euler and Navier-Stokes equations.
• 03/04/2021 Summary of the First AIAA CFD Transition Modeling and Prediction WorkshopJim Coder, University of Tennessee KnoxvilleThis seminar will cover the proceedings of the first AIAA CFD Transition Modeling and Prediction workshop, the objective of which was to assess the current state of laminar-turbulent prediction, determine best practices for transitional flow simulations, verify model implementations, and encourage improvements to CFD capabilities.
• 02/25/2021 Addressing the Challenges of the Design of Hypersonic Vehicles with SimulationsValerio Viti, Scott Marinus, Jeff Tharp & Craig Miller, Ansys Inc.The resurgence in hypersonic technology has highlighted the need to accurately and efficiently simulate these complex systems using high-fidelity computer simulations. Given the extreme costs of flight testing and the limited capabilities of ground-based wind tunnels, computer simulation is a key-enabling technology to stay ahead in the design and analysis of hypersonic vehicles. This webinar will discuss several high-profile challenges encountered by engineers when designing and analyzing hypersonic vehicles.
• 02/18/2021 Effects of Rotation on Internal Structure and Dynamics of Main-Sequence StarsIrina N. Kitiashvili, NASA Advanced Supercomputing DivisionCurrent state-of-the-art computer simulations allow us to build 3D dynamical and radiative models of stars from physical first principles with a high degree of realism. The radiative 3D dynamical stellar models obtained with the StellarBox code take into account the effects of turbulence, stellar abundances, equation of state, and radiative energy transport. This talk will discuss the effects of rotation on the turbulent dynamics and surface structure for a 1.47Msun star for rotational periods of 1 and 14 days.
• 02/11/2021 The Impact of Multi-Physics CFD Simulation in Aircraft Safety and Droplet ModelingDurrell Rittenberg & Prashanth Shankara, Siemens Digital Industries SoftwareAlthough the exact mechanism of the current pandemic transmission is not fully understood, integrators are leveraging computational methods to understand the behavior of coughs in an enclosed environment. This presentation will discuss the current state of the art of cough modeling and the extension to air cabins as well as the impact of a standard mask on droplet transmission. It will also cover several examples from current organizations leveraging CFD to improve their understanding on HVAC and cabin environments.
• 02/02/2021 High-Order Discontinuous Galerkin Method for Entry Simulations into Dusty Atmospheric EnvironmentsMatthias Ihme & Eric Ching, Stanford UniversityIn recent years, the discontinuous Galerkin method has gained considerable interest, due to high-order accuracy with a compact stencil, geometric flexibility, suitability for high-performance computing paradigms, and other benefits. However, it currently lacks a well-established infrastructure for handling complex multiphysics applications. This seminar presents advancements to the discontinuous Galerkin scheme for simulating high-speed disperse multiphase flows. A simple and robust shock capturing method is introduced.
• 01/28/2021 Introduction to the WarpIV KernelJeffrey S. Steinman, WarpIV Technologies, Inc.This introductory talk will provide a high-level overview of WarpIV Kernel capabilities and demonstrate recent work performed for NASA where four very different applications were quickly developed: (1) simulation of planetary rings as an n-body gravitational system; (2) simulation of space debris with closest approach calculations in a missile-defense scenario involving launched rockets, interceptors, and satellites; (3) numerical computation of gravitational fields for ellipsoidal planets (e.g., Saturn); and (4) superposition of radio frequencies involving large numbers of moving transmitters and receivers where packetized signals are digitized.
• 12/17/2020 High-Fidelity CFD in the Cloud — Thoughts and PerspectivesNeil Ashton, Amazon Web ServicesThis talk will focus on exploring the motivation for using cloud computing for CFD from an industry and research viewpoint. Using examples from automotive, aerospace and manufacturing we’ll look at benchmarks for a number of CFD codes using CPUs (x86 & Arm) and GPUs and we’ll look at how the development of high-fidelity CFD e.g. WMLES, HRLES, is accelerating the need for access to large scale HPC, as well as how pre- and post-processing are more easily accessed via a cloud infrastructure.
• 12/15/2020 Active Control Strategies for Compressible and Multiphase FlowsMahesh Natarajan, National Renewable Energy Laboratory (NREL)The focus of this talk is on active flow control for single and multi-phase, compressible flows. For single-phase flows, a novel method has been developed to design a linear feedback control system that utilizes the information contained within the forward and adjoint global modes of the baseflow obtained from DNS/LES. For multi-phase flows, the focus is on the control of primary atomization in sprays. An all-Mach multiphase flow algorithm is integrated into AMReX — a framework for massively parallel, block-structured adaptive mesh refinement applications. Simulations are performed to investigate the dynamics of spray breakup of a water jet in the presence of transverse, standing acoustic waves.
• 12/10/2020 Aeroacoustic Predictions for a Lift-Offset Coaxial Rotor and Urban Air Mobility AircraftHenry Jia, University of California, DavisThe first part of this seminar will highlight the acoustic characteristics of a lift-offset coaxial rotor configuration in high-speed forward flight, which are studied based on a high-fidelity Computational Fluid Dynamics (CFD) and Computational Structural Dynamics (CSD) loose coupling approach for the first time. The second part of this seminar will discuss the noise characteristics of fully electric and hybrid multi-rotor UAM aircraft in forward flight, which are investigated based on high-fidelity CFD simulations with prescribed blade motions.
• 12/01/2020 Fluid Flow Simulation with Lattice Boltzmann Methods on High Performance ComputersMathias J. Krause, Adrian Kummerländer, and Stephan Simonis, Karlsruhe Institute of TechnologyIn this seminar, an overall strategy for numerical simulations and optimization of fluid flows is introduced. The integrative approach takes advantage of numerical simulation, high performance computing and newly developed mathematical optimization techniques, all based on a mesoscopic model description and on Lattice Boltzmann Methods as discretization strategies. In the talk, particular focus is placed on the systematic approach of facing contemporary challenges in computational fluid dynamics.
• 11/05/2020 Machine Learning Tools for Predicting Solar Energetic Particle Hazards: Progress and PlansViacheslav Sadykov, BAERI, NASA Ames Research CenterIn this seminar, the first-year progress on the “Machine Learning Tools for Predicting Solar Energetic Particle Hazards” project under the NASA Early Stage Innovation STMD program will be presented. The primary objective of the project is to enhance predictions of SEPs by implementing automatic data characterization and Machine Learning (ML) tools. The first part of the seminar highlights the development of an online-accessible database that integrates a variety of solar and heliospheric data, metadata, and descriptors related to Solar Proton Events (SPEs). The second part of the seminar is dedicated to the development of “all-clear” forecasts of SEP events.
• 10/27/2020 Rapid Computational Aerodynamic Analysis for Multi-Rotor AircraftJonathan Chiew, NASA Ames Research CenterThis presentation focuses on the development of a rapid aerodynamic simulation capability for multi-rotor aircraft that provides accurate performance estimates. The first portion of presentation will discuss rotor modeling using blade element theory and integral velocity sampling. The following section will explore performance and robustness considerations throughout the entire simulation process.
• 10/15/2020 Computational Investigations of the Turbulent Heat Flux Experiments Mark Wernet, Dennis Yoder, Mike Borghi, Seth Spiegel, Justin Pesich, and Nick Georgiadis, NASA Glenn Research CenterThis two-hour presentation will cover a series of turbulent heat flux (THX) experiments at NASA'S Glenn Research Center for the agency's Transformational Tools and Technologies Project, with the goal of making detailed measurements in flows with such temperature variation and importance of turbulent heat flux. In conjunction with these experiments, there has been an extensive computational fluid dynamics effort underway to benchmark turbulent calculation methods for two of the THX experiments.
• 10/13/2020 Rapid Aerodynamic Database Generation for the X-57 Maxwell Electrified Jared Duensing and Gaetan Kenway, NASA Ames Research CenterUsing the curvilinear solver within the LAVA framework, aerodynamic databases have been developed through steady Reynolds-Averaged Navier-Stokes (RANS) computations, quantifying performance for conditions spanning the flight envelope. Additionally, unsteady RANS simulations were performed to quantify dynamic stability derivatives, results of which are used in the flight simulator by the test pilots. This talk will outline the X-57 database generation process, including initial mesh generation, validation and verification procedures, and final results, as well as summarize efficiency improvements resulting from the LAVA solver refactorization.
• 09/29/2020 PuMA and Multiscale Modeling Federico Semeraro & Krishnan Swaminathan Gopalan, Science and Technology Corporation / NASA Ames Research CenterThis presentation discusses the capabilities and modeling approach of the Porous Microstructure Analysis (PuMA) software, a computational framework to extract material properties and simulate material response. The three main components of the software, i.e., domain generation, image processing and the computation of effective material properties, will be discussed.
• 09/24/2020 Towards High-Fidelity Modeling of Arc-Jet Environments and Material Response Jeremie Meurisse, Science and Technology Corporation / NASA Ames Research CenterThis presentation will discuss the high-fidelity modeling of arc-jet environments and materials, an ongoing effort by the Entry Systems Modeling (ESM) project. The ESM project is developing and exploring high-fidelity tools for the analysis of Thermal Protection Systems (TPS). Arc-jets are unique facilities used to evaluate the performance of TPS for hypersonic vehicles. They produce high pressure and high enthalpy plasma flows to simulate the extreme heat encountered during atmospheric entry.
• 09/17/2020 DSMC Simulations for Cupid’s Arrow Arnaud Borner, Science and Technology Corporation / NASA Ames Research CenterThis presentation will discuss hypervelocity sampling in the upper atmosphere of Venus, with respect to the Cupid’s Arrow mission concept, in which a stand-alone small spacecraft (~80 cm diameter, sphere/cone geometry) is designed to skim through the Venus upper atmosphere and acquire gas samples below the homopause altitude, where the different atmospheric compounds are expected to be well mixed. The velocity of the spacecraft where sampling would occur is expected to be between 10.5 km/s and 13.1 km/s, depending on the trajectory chosen.
• 09/10/2020 Scale Resolving Simulations of Corner-Flow Separation in a Wing-Body Juncture Aditya Ghate, Science and Technology Corporation / NASA Ames Research CenterThis seminar will evaluate two distinct simulation methodologies, Delayed Detached Eddy Simulation (DDES) and stress-based Wall-modeled Large Eddy Simulation (WMLES), using structured overset grid curvilinear grids for the NASA Juncture flow model. While both methodologies are shown to mitigate the primary shortcomings of steady state Reynolds-Averaged Navier-Stokes (RANS) simulations, several unresolved aspects will be identified.
• 08/27/2020 Evaluation of Wall-modeled LES for Turbulent Separated Flows Prahladh Iyer, National Institute of AerospaceScale-resolving methods are becoming increasingly popular for the prediction of turbulent separated flows, and recent studies are promising when compared to the more widely used Reynolds-Averaged Navier-Stokes (RANS) methodology. This seminar will evaluate the performance of the stress-based wall-modeled large eddy simulation (WMLES) methodology for a number of turbulent separated flow test cases using an unstructured finite volume solver. Detailed comparisons with available experimental and/or higher-fidelity DNS/LES data will be used to assess the performance.
• 08/20/2020 Simulation of a Turbulent Flow Subjected to Favorable and Adverse Pressure GradientsAli Uzun, National Institute of AerospaceThis talk will discuss the results from a direct numerical simulation of an initially turbulent boundary layer passing over a wall-mounted "speed bump" geometry. The speed bump, represented in the form of a Gaussian distribution profile, generates a favorable pressure gradient region over the upstream half of the geometry, followed by an adverse pressure gradient over the downstream half. The boundary layer approaching the bump undergoes strong acceleration in the favorable pressure gradient region before experiencing incipient or very weak separation within the adverse pressure gradient region.
• 08/11/2020 Wall-Modeled LES of Turbulent Flow Past Airfoils and Periodic HillsRavi Samtaney, The King Abdullah University of Science and Technology (KAUST)This talk presents wall-modeled large-eddy simulation (WMLES) of turbulent flow past airfoils and periodic hills. To avoid the challenging resolution requirements of the near wall region, a virtual wall model in generalized curvilinear coordinates is developed and incorporated with the non-equilibrium effects via proper treatment of the momentum equations. By combining the wall model with the stretched-vortex subgrid-scale model, the WMLES approach to three different airfoil cases is applied, spanning different geometrical parameters, different attack angles and low to high Reynolds number based on chord length.
• 08/04/2020 Fighting the Spread of Pathogens in Passenger Aircraft Cabins: An Approach Using Computer SimulationsValerio Viti & Kishor Ramaswamy, Ansys, IncThis talk will explore how high-fidelity physics-based computer simulations can be used to help with the abatement of the virus transmission in a cabin's air. It will show how CFD simulations of the flow patterns inside a passenger cabin can be used to suggest new best practices for safe air travel. This seminar will show how optical simulation and CFD tools can be used to improve the sterilization of the cabin via UV rays and electrostatic sprays.
• 07/28/2020 Investigation on the Dispersion Driven by a Condensed Phase Explosion in an Urban EnvironmentCharline Fouchier, The von Karman Institute for Fluid DynamicsThis seminar will discuss a study that aims to provide a quantitative experimental database on the dispersion driven by an explosion in an urban environment, in order to validate recently developed simplified models. To achieve this goal, experimental techniques are developed and applied on heterogenous explosions inside a controlled reduced-scale urban environment. Existing experimental techniques have been extended and validated for the large dynamic ranges involved in the explosively driven dispersion and can be used for further complex flows investigations.
• 07/23/2020 Mesh Effects on Flow Solutions for a 2D Multi-Element Airfoil Using Structured Overset MethodsAndrew Chuen, Computational Aerosciences BranchThe seminar will evaluate current best-practices for mesh generation in a structured overset framework to determine their effects on the accuracy and convergence of the flow solution on a two-dimensional sectional cut of the High-Lift Common Research Model (HLCRM) wing. Additional investigations in “C” versus “O” mesh topologies and resolution of various flow features, such as shear layers and wakes, are also considered. A grid convergence study is used to evaluate the accuracy of the final best-practice mesh.
• 07/16/2020 Computational Flame Propagation Studies in Support of Launch Vehicle Risk AssessmentAshley Coates, Computational Aerosciences BranchThe seminar will discuss work being done to use CFD simulations to better understand flame propagation mechanisms and sensitivities in an effort to improve flame speed inputs to risk models for space launch vehicles. This presentation will highlight two groups of studies: one focused on mechanisms of deflagration to detonation transition in obstructed flows, and another focused on the influence of underlying parameters on flame propagation. Comparisons of the CFD results with both experimental data and engineering model results are also presented.
• 07/09/2020 Computational Investigations of Surface-Normal Pneumatic Active Aerodynamic Load Control for Lift Enhancement and Separation Mitigation in High-Lift SystemsSheida Hosseini, Computational Aerosciences BranchThis talk will propose to use surface-normal pneumatic Active Flow Control—so-called microjets—near the flap trailing edge of an aircraft wing to control high-lift performance. We present various computational microjet characteristic investigations in a building block approach starting on a two-dimensional airfoil and concluding on a three-dimensional airplane wing/body configuration.
• 06/30/2020 Projection-based Model Order Reduction and Hyperreduction of Turbulent Flow ModelsSebastian Grimberg, Stanford UniversityProjection-based model order reduction (PMOR) methods offer the ability to dramatically reduce this computational cost by generating compact, low-dimensional models for which solutions can be obtained in near real-time while still retaining the accuracy of an associated high-fidelity, high-dimensional model for the time and parameter domain of interest. This talk will address some of these challenges, demonstrating in the end PROMs for a number of large-scale, unsteady, turbulent flow applications which showcase the potential of PMOR for nonlinear CFD models with multiscale physics. This talk will also present an investigation of the role of projection in the numerical stability of PMOR for convection-dominated flow problems, ultimately disproving an often-stated claim in the literature with the support of several numerical examples.
• 03/05/2020 Cartesian Mesh Simulations and Farfield Propagation Results for the 3rd AIAA Sonic Boom Prediction WorkshopWade M. Spurlock, NASA Advanced Supercomputing DivisionSimulation results are presented for all test cases prescribed in the Third AIAA Sonic Boom Prediction Workshop. The workshop is decomposed into two problems: nearfield, high-fidelity CFD and farfield acoustic propagation. In our work, an inviscid, embedded-boundary Cartesian-mesh flow solver is used to compute near-field pressure signatures, which are then propagated to the ground to form “boom carpets”—pressure signatures and ground noise metrics at a range of specified distances and off-track angles.
• 02/27/2020 Prediction of Real-World External Aerodynamics Using Wall-Modeled Large-Eddy SimulationAdrian Lozano-Duran, Stanford UniversityThe use of computational fluid dynamics for external aerodynamic applications has been a key tool for aircraft design in the modern aerospace industry. In the last decades, Wall-Modeled Large-Eddy Simulation (WMLES) has gained momentum as a cost-effective approach for both scientific research and industrial applications. In this talk, we discuss the performance of WMLES for external aerodynamic applications, with emphasis on realistic commercial aircrafts.
• 02/20/2020 Massively Parallel Anisotropic Meshing Framework for CFD and Data SciencesElie Hachem, Mines ParisTechThis presentation will share numerical developments built on a ground-breaking parallel adaptive anisotropic mesh refinement based on a posteriori error estimation for multiphysics challenging simulations. In this work, the team made several strategic investments to increase the scalability and the automation of mesh operations within the simulation workflow. This is already essential to perform simulations on pre-Exascale supercomputers and mandatory for future Exascale simulations. Additionally, they have developed an immersed methodology that allows the automatic creation of highly complex simulation models from CAD-geometries and then the optimization and testing the code on different supercomputers. This seminar will share all the details about these two unique characteristics, precisely the immersed methods and the parallel anisotropic meshing.
• 02/18/2020 Installed Performance Modeling & Simulation for Antennas – "A Good Antenna, Righteously Placed"Shawn Carpenter, ANSYS Electronics Business UnitThe design of successful antennas and antenna systems for coexisting RF sensor and communication systems is a growing challenge for today's multi-function platforms. The design of high-performance antennas may require high frequency electromagnetic analysis over a dimensional range that spans 5 or 6 orders of magnitude and which may include full platforms that extend thousands of electrical wavelengths in size. To accomplish the necessary simulations in an efficient manner—with high fidelity—requires multiple efficient EM simulation solver approaches which must be linked or hybridized for a smooth analysis progression.
• 02/12/2020 The Mission and Requirements of a Turbulence ModelPhilippe Spalart, The Boeing Company"The Mission" half of this talk will argue that a model should be essentially universal, considering that a single flow field can contain many deeply different flow modules. The differential equations and boundary conditions must be absolutely complete. Its physical rationale is desirable, as is version control with full clarity. "The Requirements" half of the talk could serve a purpose in the era of Machine Learning (ML), which brings in colleagues with little "turbulence culture."
• 02/06/2020 A Computational "Rheometer" for Turbulent FlowsAli Mani, Stanford UniversityThis study presents a numerical procedure, called the macroscopic forcing method (MFM), which reveals the differential operators acting upon the mean fields of quantities transported by underlying fluctuating flows. Specifically, MFM can reveal differential operators associated with turbulent transport of scalars and momentum. This seminar will present this methodology by considering canonical problems with increasing complexity. It will also show a cost-effective generalization of MFM for analysis of non-homogeneous and wall-bounded flows, where eddy diffusivity is found to be a convolution acting on the macroscopic gradient of transported quantities.
• 02/04/2020 Icing on UAVsRichard Hann, Norwegian University of Science and Technology (NTNU) & UBIQ AerospaceThis talk will discuss a joint effort between NASA Ames and NASA Langley Research Centers with the goal to analyze the Mach 0.745 variant of the Boeing Transonic Truss-Braced Wing (TTBW) Design. Two different flow solvers, LAVA and USM3D, were used to predict the TTBW flight performance. Sensitivity studies related to mesh resolution and numerical schemes were also conducted to define best practices for this type of geometry and flow regime.
• 01/28/2020 Computational Simulations of a Mach 0.745 Transonic Truss-Braced Wing DesignDaniel Maldonado, NASA Advanced Supercomputing DivisionThis talk will discuss a joint effort between NASA Ames and NASA Langley Research Centers with the goal to analyze the Mach 0.745 variant of the Boeing Transonic Truss-Braced Wing (TTBW) Design. Two different flow solvers, LAVA and USM3D, were used to predict the TTBW flight performance. Sensitivity studies related to mesh resolution and numerical schemes were also conducted to define best practices for this type of geometry and flow regime.
• 01/23/2020 How to Compute with Schrödinger's Cat: An Introduction to Quantum ComputingEleanor Rieffel, NASA Ames Research CenterThis talk will introduce key concepts underlying quantum computing and correct misconceptions, as well as discuss research being done by NASA's QuAIL group on quantum algorithms, quantum supremacy, elucidating quantum resources for computation, quantum programming and compilation, quantum-inspired classical algorithms, and assessing future applications of quantum computing, all within the broader context of the rapidly evolving field.
• 12/18/2019 Quadcopter Noise Prediction with the Lattice Boltzmann MethodFrancois Cadieux, NASA Advanced Supercomputing DivisionUsing the Launch, Ascent, and Vehicle Aerodynamics (LAVA) software’s Cartesian adaptive mesh refinement capability, this seminar will discuss the established best practices and assess the accuracy and cost of small quadcopter noise predictions with the Lattice-Boltzmann method (LBM) coupled with a far-field acoustics solver. Results from the finest scale-resolving LBM simulations are in good agreement with wind tunnel measurements across a wider range of frequencies than has ever been demonstrated.
• 11/12/2019 Applied Artificial Intelligence for Science &Exploration Enabled by Public-Private PartnershipsMadhulika Guhathakurta, NASA Ames Research CenterNASA Frontier Development Laboratory (FDL) is an applied Artificial Intelligence (AI) research partnership focused on challenges in space science and exploration. The recent advances in Artificial Intelligence (AI) capabilities are particularly relevant to NASA science and exploration goals because there is growing evidence that AI techniques can improve our ability to model, understand and predict our environment using the petabytes of data already within NASA archives. The 2019 program, held at the SETI Institute and NASA Ames Research Center focused on AI based science opportunities within the fields of Earth Observation applied to flood prediction and response, Lunar Resources, Astronaut Health, Heliophysics and Space Weather. The program is an 8-week concentrated R&D deep-dive process using the latest developments in machine learning and access to cutting-edge academic research and enormous compute resources provided by FDL’s commercial AI partners as well as detailed industry partner case studies, showcasing the potential application of AI to space challenge domains.
• 11/07/2019 In-flight Icing for Low-Reynolds Number AircraftKim Lynge Sorensen, UBIQ AerospaceThis talk will cover work trying to solve the in-flight icing problem for small unmanned aircraft systems and how that search has evolved into a company focused on solving the entirety of this highly complex problem, with the help of world-renowned research scientists. It will cover the obstacles we faced in the beginning, including the work we did at NASA Ames, and the challenges we are facing now that we have what we believe to be a viable solution.
• 11/05/2019 Asteroid Impact Risk: The Uncertain Outcome of Deflection MissionsClemens Rumpf, NASA Advanced Supercomputing DivisionThe threat of asteroid impacts on the Earth can be mitigated through defection missions. Here we investigate the effect of pre-designed deflection missions on the risk profile of the fictitious impact scenario 2019 PDC under large uncertainties. The impact risk analysis is based on a statistical approach. We sample orbital and physical property distributions for the asteroid that provide a complete representation of possible impact scenarios.
• 10/29/2019 Computational Modeling of Space Re-entry Aerothermodynamics and Magnetized Plasmas with COOLFluiDAndrea Lani, Katholieke Universiteit LeuvenThe COOLFluiD (Computational Object Oriented Libraries for Fluid Dynamics) project, which started in 2002 as a joint effort between the Von Karman Institute for Fluid Dynamics (VKI) and the Center for mathematical Plasma Astrophysics (CmPA) at the University of Leuven (KUL), has led to the development of a world-class open source platform for HPC and multi-physics modelling. Within this framework, research efforts have been devoted particularly to the modeling of space re-entry aerothermodynamics and magnetized plasmas.
• 10/03/2019 Hitting the Roof(line): Should I Optimize for Compute, Memory, or Both?Dunni Aribuki, Intel CorporationBuilding and deploying applications that run efficiently on modern hardware is complicated. Even the most skillful developers often struggle to understand performance in relation to hardware limitations, especially memory bandwidth and computational peaks. This talk presents the Roofline Model that provides a visual representation of an application’s performance against hardware-imposed performance ceilings. Roofline analysis provides developers with an optimization strategy to squeeze maximum performance out of their code with minimal time or effort. We will begin by discussing how roofline analysis helps to guide code optimizations for both memory and compute.
• 10/03/2019 Towards Fully-Resolved Particulate-Induced Transition Simulations for High-Speed Boundary-Layers with an Immersed Boundary MethodOliver M. F. Browne, University of KentuckyThis talk will present a numerical approach to model particulate-induced transition in the upper atmosphere (stratosphere) relevant for high-speed (high supersonic/hypersonic) vehicles. Various types of particulates with different origins and a wide range of properties are present in the stratosphere and could provide the threshold disturbance energy to cause boundary-layer transition. Atmospheric particulates impinging on the surface of high-speed vehicles trigger a wavepacket inside the boundary layer which, based on the flow and particle conditions, can grow substantially and provide a path to turbulence.
• 09/19/2019 Fully-Coupled Fluid-Structure Interaction Simulations of a Supersonic ParachuteJonathan Boustani, NASA Advanced Supercomputing DivisionThis seminar will discuss a validated computational fluid-structure interaction method for simulating the complex interaction between the large deformation of very thin, highly deformable structures and compressible flows, which is extended to consider large-scale problems in supersonic flows using parallel computing. The method is applied to large deformation fluid-structure interaction validation cases before being applied to the inflation of a supersonic parachute in the upper Martian atmosphere where the goal is to demonstrate the capabilities of the method when considering large-scale problems in supersonic flows.
• 09/12/2019 Turbulence, from Theory to High-Lift Systems?Philippe Spalart, The Boeing CompanyTwo recent lines of thought are covered. The first addresses the path from DNS data to RANS models, with an eye for Artificial Intelligence. Possible “structural conflicts” in the RANS models are discussed, and the overall weak link from DNS to RANS is less surprising. The second covers the CFD Vision 2030 proposals, in particular that of substituting turbulence-resolving simulations of various kinds for the steady RANS models, which appear to have run their course especially for high-lift flows. The exploration of the flow fields suggests that orders of magnitude in resolution are needed before the simulations of full configurations are well-resolved.
• 09/05/2019 A Constraint-Based Approach to Automatic Data PartitioningWonchan Lee, Stanford UniversityIn this talk, we present a constraint-based approach to automatic data partitioning. By introducing abstractions for first-class data partitions, we express a space of correct partitioning strategies. Candidate partitions are characterized by partitioning constraints, which can be automatically inferred from data accesses in parallelizable loops. Constraints can be satisfied by synthesized partitioning code or user-provided partitions. We demonstrate that programs auto-parallelized in our approach are easily composed with manually parallelized parts and have scalability comparable to hand-optimized counterparts.
• 08/20/2019 Using GitLab for Modern Application DevelopmentDan Gordon, GitLabModern software development involves many steps which typically are accomplished by many tools strung together. The toolchain tax that results can drastically slow down the ability to innovate. GitLab helps teams to efficiently develop and deliver their software projects, quickly and with high quality. GitLab provides a DevOps platform delivered as a single application, freeing teams to put all their energy into innovating. In this session we'll look at how GitLab can help you create your application, build it, test it, secure it, package it, release it, and monitor it, all out of the box. Just add your code.
• 08/13/2019 Efficient Near-Field to Mid-Field Sonic Boom Propagation using a High-Order Space Marching MethodJeffrey Housman, NASA Ames Research CenterAn efficient strategy for propagating sonic boom signatures from a near-field Computational Fluid Dynamics (CFD) solution to the mid-field is presented. The new approach leads to more than a factor of two reduction in overall computational resources compared to the current method used to propagate near-field sonic booms to the ground. Accuracy and efficiency of the near-field to mid-field process is demonstrated using a selection of test cases from the AIAA Sonic Boom Prediction Workshops.
• 08/07/2019 Predictions of Slat Noise from the 30P30N at High Angles of Attack using Zonal Hybrid RANS-LESJeffrey Housman, Computational Aerosciences Branch, NASA Advanced Supercomputing DivisionAeroacoustic predictions of slat noise from the 30P30N three-element high-lift system at high angles of attack are presented using a zonal hybrid RANS-LES method. The simulations are part of the 5th AIAA Benchmark problems for Airframe Noise Computations (BANC-V) Workshop. An economical approach utilizing structured overset grids with spatially varying span-wise grid resolution and a high-order accurate finite difference method is described.
• 07/30/2019 2019 Summer Intern PresentationsThis seminar will showcase presenations from the Computational Aerosciences Branch Summer 2019 interns. Presentations include: Building the SLS Artemis-2 Booster Separation Aerodynamic Database, One Dimensional Point Distribution Using Geometric Stretching, Development of a Triangulation Quality Checker for LAVA, Development of a Utility to Automatically Generate Trajectory Files Based on User Prescribed Motions, Development of a Mesh Redistribution Algorithm for Structured Curvilinear Meshes, Uncertainty Quantification with Cart3D and QUEST, and Unstructured CFD Support for Commercial Supersonic Technology Wind Tunnel Tests.
• 06/27/2019 Hybrid RANS/LES Simulation of Jet Surface Interaction NoiseGerrit-Daniel Stich, NASA Advanced Supercomputing DivisionNASA's Commercial Supersonic Technology (CST) project has formulated a technical challenge to design a quiet propulsion system for a low boom supersonic aircraft that meets Federal Aviation Authority's airport noise regulations with sufficient margin. Development of carefully validated computational tools are necessary for critically evaluating installation concepts that are currently being proposed to meet the technical challenge. As a first step towards predicting noise reduction due to radical installation concepts from first principles, we simulate the noise generated by a high speed turbulent round jet near a simple planar surface.
• 06/13/2019 Computational Simulations of Electric Propulsion Aircraft: The X-57 MaxwellJared Duensing, NASA Advanced Supercomputing DivisionThe X-57 Maxwell is NASA’s latest electric airplane concept that has been simulated using CFD to develop multiple aerodynamic databases. This talk presents one possible approach to establishing best practices for mesh resolution, numerical discretization, turbulence modeling, and propulsion modeling prior to database generation. Preliminary database results have shown that these practices can potentially reduce error in X-57 aerodynamic loads and moments relative to experiment by up to 14%. Sample database results with and without propulsion will also be presented and discussed.
• 06/06/2019 High-Order Shock-capturing Methods for Study of Shock-induced Turbulent Mixing with Adaptive Mesh Refinement SimulationsMan Long Wong, NASA Advanced Supercomputing DivisionThe shock-induced instabilities at interfaces separating materials of different densities and the subsequent turbulent mixing are commonly found in natural phenomena and engineering applications with high-speed flows. This seminar will discuss a type of high-order shock-capturing schemes that is improved to preserve fine-scale features in smooth regions with minimal dissipation, while still having the ability to provide sufficient numerical dissipation to capture shocks and discontinuities robustly.
• 05/14/2019 Inertial Particles in Wall-Bounded Turbulence: Turbophoresis, Wall-Modeled Large-Eddy Simulations, and Particle-Particle CollisionsPerry Johnson, Center for Turbulence Research, Stanford UniversityIn wall-bounded turbulent flows, heavy particles tend to accumulate in the near-wall region due to a phenomenon known as turbophoresis. These enhanced particle concentration levels can depend strongly on the interaction of particles with coherent flow structures, which presents challenges for wall-modeled large-eddy simulations (LES). This talk will explain how the presence of near-wall structures influences particle dynamics and explore how the relative importance of this interaction depends on particle and flow properties, primarily the friction Stokes number. Implications for wall-modeled LES with Lagrangian particle tracking will be drawn and briefly demonstrated.
• 05/09/2019 Reduced-Order Modeling of Laminar-Turbulent Transition in Large-Eddy SimulationsPhilipp Hack, Center for Turbulence Research, Stanford UniversityThe modeling of the laminar region and the prediction of the onset of transition remain key challenges in the numerical simulation of boundary layers. The issue is of particular relevance in wall-modeled large eddy simulations which require 10 to 100 times higher grid resolution in the thin laminar boundary layer than in the turbulent regime (Slotnick et al., NASA/CR-2014-218178, 2014). This talk examines the potential of the nonlinear parabolized stability equations (PSE) to provide an accurate, yet computationally efficient treatment of the growth of disturbances in the pre-transitional flow regime.
• 04/09/2019 Orion Launch Abort System AcousticsFrancois Cadieux, NASA Advanced Supercomputing DivisionThe Orion Launch Abort System (LAS) is designed to carry the Orion spacecraft and its crew away from the rocket if a problem occurs on the launch pad after ignition or during ascent. We produced detailed turbulence-resolving simulations to help collaborators on the Orion Loads and Dynamics team assess key aspects of the launch abort environment: the strength of ignition overpressure waves and the levels of acoustic vibrations generated by the hot plumes. Using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) software’s Cartesian Adaptive Mesh Refinement (AMR) capability, we were able to accurately reproduce ground test and wind tunnel test measurements and trends.
• 04/04/2019 Ansys Fluent Mosaic Meshing for CFD SimulationsHoang Vinh, Ansys, Inc.Transitioning between varying types of mesh elements in complex geometries and flow regimes has long been a major simulation challenge. Ansys is addressing this challenge with the introduction of Mosaic technology that automatically connects different types of meshes with general polyhedral elements. This seminar will discuss the initial implementation of this technology, which maintains layered poly-prism elements in the boundary layers, fills the bulk region with computationally-efficient and highly-accurate octree hexahedral elements, and conformally connects these two meshes with high-quality polyhedral elements.
• 03/28/2019 Input-Output Analysis of High-Speed Turbulent Jet NoisesJinah Jeun, Center for Turbulence Research, Stanford UniversityIn this talk we investigate amplifying behavior of small perturbations about Reynolds-averaged Navier-Stokes solutions of high-speed turbulent jets using input-output (I/O) analysis. Inspired by control theory in electrical engineering, our method examines how input forcing (jet turbulence) leads to output noise.
• 03/19/2019 Multi-GPU FFT Performance on Different Hardware ConfigurationsKevin Roe, Maui High Performance Computing CenterThe performance of multi-GPU systems are characterized in an effort to determine the viability of these systems to run physics based applications using Fast Fourier Transforms.
• 03/13/2019 Lattice Boltzmann Equation: Its Mathematical Essence and Key PropertiesLi-Shi Luo, Old Dominion UniversityThis presentation focuses on the mathematical origin and properties of the lattice Boltzmann equation (LBE)—a solution method for the nearly incompressible Navier-Stokes equations (NSE). Unlike the traditional or conventional methods in CFD which are based on direct discretizations of NSE (i.e., finite difference, finite volume, finite element, spectral, and discontinuous Galerkin methods), the LBE is derived from the Boltzmann equation with a linearized collision term.
• 03/07/2019 OVERFLOW results for the Juncture Flow ExperimentHenry Lee, Science and Technology Corporation/NASA Advanced Supercomputing DivisionThis presentation will focus on the CFD analysis done in support of NASA's Juncture Flow Experiment (under NASA’s Transformational Tools and Technologies Project [T3]). The first phase of the Juncture Flow experiment, performed in NASA Langley’s 14- by 22-Foot Subsonic Tunnel, has been completed. Comparisons between OVERFLOW CFD simulations and wind tunnel experimental results will be shown.
• 02/21/2019 A Fast Pressure-Correction Method for Incompressible Flows Over Curved WallsAntonino Ferrante, University of WashingtonThis seminar will describe a newly developed pressure-correction method for simulating incompressible flows over curved walls. We chose the orthogonal formulation of the Navier-Stokes equations in curvilinear coordinates vs the generalized curvilinear coordinates because the computational cost of advancing the numerical solution of the governing equations in time is substantially reduced as the orthogonal formulation does not contain cross-derivatives in the advection, diffusion, Laplacian, and gradient operators. As a result, the numerical stencils of the finite difference approximations to these operators mirror that of the Cartesian formulation.
• 12/13/2018 Gabor Mode Enrichment in Large Eddy Simulations of Turbulent FlowsAditya Ghate, Science and Technology Corporation, NASA Advanced Supercomputing DivisionRecent advances in wall-modeled Large Eddy Simulations (WMLES) allow for accurate prediction of first order turbulence statistics (means) using very low-resolution (coarse) computational grids. However, several applications such as unsteady load prediction, surface vibration, acoustic radiation and particle laden turbulence require highly accurate representation of a large spatio-temporal range of dynamically active scales that are present in high Reynolds number turbulence. The research addresses this emerging challenge in LES, and the new model substantially extends the spatio-temporal bandwidth of the solutions computed using low-resolution simulations with unprecedented accuracy. This "enrichment" is accomplished by representing subfilter scales in terms spatially and spectrally localized Gabor modes.
• 12/04/2018 New Features in Chimera Grid Tools Version 2.2William Chan, Computational Aerosciences Branch, NASA Advanced Supercomputing DivisionChimera Grid Tools (CGT) is a software package containing various modules for pre- and post-processing of computational simulations using overset grids. Most of the talk will focus on the new features introduced in version 2.2 released in June of 2018. Main topics will include a geometry interface via the Engineering Sketch Pad (ESP) open source library, various diagnostics for grid and domain connectivity quality, a library for automatic type and attributes detection for file I/O, a general cut-plane tool for grid and solution visualization, enhancements to the Script Library, and a script development tutorial for the steps in an overset CFD analysis process.
• 11/27/2018 Efficient Aerodynamic Simulation of Multi-Rotor VehiclesJonathan Chiew, Computational Aerosciences Branch, NASA Advanced Supercomputing DivisionThis seminar will describe development of a scalable rotor model for the Cart3D inviscid flow solver. The rotor forces are computed using blade element theory and imparted to the flow with momentum and energy source terms. In addition, techniques for handling low Reynolds number aerodynamics in airfoil tables and vehicle trim will be discussed. Results from strong scaling and mesh convergence tests will be presented as well as simulations of both hovering, axial, and edgewise forward flight.
• 11/01/2018 Strand Mesh Generation Using Minimum Distance FieldsBeatrice Roget, Science and Technology Corp., NASA Ames Research CenterAnisotropic prismatic/strand meshes are often used to capture viscous boundary layer effects in RANS simulations of high Reynolds number flows. This presentation describes a new algorithm for generation of these prismatic meshes using the minimum distance field of the surface tesselation. The algorithm is based on initial point placement using both the closest point on this iso-surface, and the direction of best visibility.
• 10/25/2018 Integrated Simulation System for Soft MattersTaku Ozawa and Hiroya Nitta, JSOL CorporationSoft matter, such as resins, rubber materials, film, adhesive, and so on, has a multiscale structure. Computer simulation is an effective tool for understanding the mechanism of how the physical properties are exhibited. However, it is necessary to properly use the methods for each scale. The integrated simulation system for soft matter, OCTA and J-OCTA, include useful modeling methods and simulation engines/solvers to perform multi-scale simulation.
• 10/23/2018 Application of a Pore Network Pore-Scale Simulation for Analysis of Single and Two-phase Flow in Porous MaterialsDaniel Niblett, University of ManchesterTraditional simulation techniques for flow and transport at the pore scale are often computationally slow and expensive, as well as being limited to domain size. The new methodology proposed here, allows the same simulation to be completed using a single processor with a shorter duration, without the loss of accuracy. Thus, allowing for larger domain sizes to be simulated at a faster rate. Using this highly cited pore network code, further developments are being established through industrial research. This seminar will describe the methodology that allows our code to simulate static and dynamic properties efficiently, including the scope to expand to other porous material processes. This method has the potential to simulate flows within the whole spectrum of materials from rocks and soils to textiles and paper.
• 10/10/2018 Assessment of Rotorcraft Download Using Helios v8Andrew Wissink, US Army Aviation Development Directorate, NASA Ames Research CenterRotorcraft download is an important design consideration for the design of hovering vehicles. High fidelity Computational Fluid Dynamics (CFD) predictions of download are time consuming to compute and the presence of unsteady bluff-body ow shedding over the helicopter fuselage challenges CFD's ability to predict correct drag. This paper investigates the application of HPCMP CREATETM-AV Helios Version 8 for download prediction. In particular the application of the automated runtime strand mesh generation that is a new feature of the mStrand solver in Hv8 is investigated and compared to results obtained with the Unstructured FUN3D and Structured curvilinear OVERFLOW solvers that have been used for download calculations in the past. Results are presented for the JVX model-test which includes both isolated rotor calculations as well as rotor/wing interactions.
• 09/06/2018 High-Order Upwind Methods for Second-Order Wave Equations on Overlapping GridsJordan Angel, Science & Technology Corporation, NASA Ames Research CenterThis presentation will discuss a novel high-order upwind schemes for the second-order wave equation. First, we develop schemes for the wave equation written as a first-order in time and second-order in space system. These schemes are applied to Maxwell's equations written in second-order form. Interfaces and physical boundaries are described with composite overlapping structured grids and coupled with interpolation and high-order interface conditions. Second, a reformulated upwind scheme is presented that considers several optimizations to the first-order in time system. This reformulated scheme discretizes the second-order wave equation directly and is seen to be much more efficient while still retaining the essential stability properties of the first-order in time scheme.
• 08/23/2018 Toward High Performance Computing of Compressible Flows using Lattice Boltzmann MethodRobert Tramel and Gabriel Nastac, Kord TechnologiesAs computer architecture becomes more parallel, numerical simulations must follow suit and exploit parallel algorithms effectively. One particular type of parallel algorithm that has become increasingly popular for simulating fluid dynamics in recent decades is the Lattice Boltzmann Method (LBM). The Boltzmann equation and Low-Mach LBM are briefly described. LBM extensions to transonic and supersonic compressible flows for ideal gases are discussed. Preliminary results for 2D flows are presented. Upcoming work involves investigating accuracy and speed of the method with respect to existing NASA solvers including NASA OVERFLOW and NASA FUN3D on canonical problems.
• 08/21/2018 Intelligent Databases and Machine-Learning Forecast of Solar FlaresViacheslav (Slava) Sadykov, New Jersey Institute of TechnologyThe growing needs for the accurate Space Weather Forecasts motivate the researchers to implement comprehensive prediction algorithms for solar transient events (flares, coronal mass ejections, filament eruptions). The first part of the talk will present an Interactive Multi-Instrument Database of Solar Flares which is an attempt to integrate the flare records from different satellites and ground-based observatories and provide a search for uniquely-identified flare events based on their physical descriptors. The second part of the talk will give a brief overview of the current attempts to predict the solar flares using the characteristics of the magnetic fields obtained by the HMI instrument on Solar Dynamics Observatory.
• 08/07/2018 Introduction to Computational Fluid Dynamics – Lecture 14Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 14 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will continue to introduce high-resolution upwind schemes.
• 08/02/2018 Introduction to Computational Fluid Dynamics – Lecture 13Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 13 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will begin introducing high-resolution upwind schemes.
• 07/31/2018 Introduction to Computational Fluid Dynamics – Lecture 12Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 12 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will discuss an explicit finite-volume algorithm with multigrid.
• 07/26/2018 Introduction to Computational Fluid Dynamics – Lecture 10 & 11Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 10 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will continue to cover Euler and Navier-Stokes equations and an implicit finite-difference algorithm.
• 07/26/2018 Ultra-Efficient Commercial VehiclesJim Coder, University of Tennessee, KnoxvilleThe University of Tennessee is leading a multi-disciplinary, multi-institutional research effort to mature slotted, natural-laminar-flow technology for flight Mach and Reynolds numbers based on the Boeing Transonic Truss-Braced Wing (TTBW) aircraft. Research activities are divided into three phases: Technology Development, Technology Integration, and Technology Demonstration, with a goal of a capstone transonic wind-tunnel test in the final year of the project.
• 07/24/2018 Introduction to Computational Fluid Dynamics – Lecture 9Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 9 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will begin to cover Euler and Navier-Stokes equations and an implicit finite-difference algorithm.
• 07/19/2018 Introduction to Computational Fluid Dynamics – Lecture 8Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 8 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will cover factored forms.
• 07/19/2018 Extension of d’Alembert’s Paradox for Elongated Bodies and A Curious Theoretical Prediction for Turbulent DuctsPhilippe Spalart, The Boeing CompanyA two-part presentation. Part one will address the extension of d’Alembert’s Paradox for elongated bodies, as applied to the entire force vector and not only the drag. A new theorem is presented showing that for elongated bodies such as trains, at zero angle of attack, the forces on the nose and tail are shape-independent and are zero separately, rather than canceling each other. Part two will cover theoretical prediction for turbulent ducts, which shows that the application of the law of the wall and defect law to non-circular ducts, such as elliptical ones, leads to the unexpected prediction that the skin friction is uniform around the perimeter.
• 07/18/2018 Turbulence Prediction in CFD: From One-Equation Models to Large-Eddy-Simulation HybridsPhilippe Spalart, The Boeing CompanyThe presentation begins with a history of the Spalart-Allmaras one-equation model, at NASA Ames and Boeing. It includes the initial impulse from Lomax and Baldwin, the publication difficulties, a perspective on other one-equation models, and a discussion of the model’s strengths and weaknesses. We then address the roles of RANS and LES, our “allies” in future turbulence treatments. The enduring limitations of each approach, rooted in physics and/or computing cost, are discussed leading to the need for hybrid RANS-LES treatments long into the future in most aerospace, transportation, energy, and atmospheric applications.
• 07/17/2018 Introduction to Computational Fluid Dynamics – Lecture 7Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 7 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will cover numerical dissipation.
• 07/10/2018 Introduction to Computational Fluid Dynamics – Lecture 5Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 5 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will continue to cover time-marching methods of ODE's.
• 07/03/2018 Introduction to AMReX A New Framework for Block-Structured Adaptive Mesh Refinement CalculationsAndrew Myers, Lawrence Berkeley National LaboratoryAMReX is a new software framework that supports the development of block-structured adaptive mesh refinement (AMR) algorithms for solving systems of partial differential equations on exascale architectures. AMR reduces the computational cost and memory footprint compared to a uniform mesh while preserving the essentially local descriptions of different physical processes in complex multiphysics algorithms. This talk will give an overview of the software components provided by AMReX and how those components are used to support different applications that use the framework.
• 06/28/2018 Eulerian Models for the Description of Polydisperse Sprays: From Fundamental Issues to Industrial Applications and HPCMarc Massot, Centre de Mathématiques Appliquées, Ecole PolytechniqueThis seminar will mainly focus on a disperse liquid phase carried by a gaseous flow field, which can be either laminar or turbulent. However, this spray can be polydisperse, constituted of droplets with a large size spectrum. Thus, such flows involve a large range of temporal and spatial scales, which have to be resolved in order to capture the dynamics of the phenomena and provide reliable and eventually predictive simulation tools. Even if the power of the computer resources regularly increases, such very stiff problems can lead to serious numerical difficulties and prevent efficient multi-dimensional simulations.
• 06/21/2018 Introduction to Computational Fluid Dynamics – Lecture 4Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 4 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will cover the Semi-Discrete Approach and Time-Marching Methods for ODE's.
• 06/19/2018 Introduction to Computational Fluid Dynamics – Lecture 3Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 3 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will cover Modified Wave Number Analysis and the Semi-Discrete Approach.
• 06/14/2018 Introduction to Computational Fluid Dynamics – Lecture 2Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 2 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session will cover Finite-differences, Taylor Tables, and compact schemes.
• 06/12/2018 Introduction to Computational Fluid Dynamics – Lecture 1Thomas H. Pulliam, NASA Advanced Supercomputing Division; David Zingg, University of Toronto Institute for Aerospace SciencesPart 1 of a 14-part lecture series. This series will help participants develop an understanding of computational fluid dynamics (CFD) and provide an opportunity to practice numerical solution techniques as applied to the equations governing fluid mechanics and heat transfer. This session introduces the course and covers Euler Wave Equations.
• 05/10/2018 Formulation and Implementation of Inflow/Outflow Boundary Conditions to Simulate Propulsive Effects ModelDavid Rodriguez, Science and Technology CorporationBoundary conditions appropriate for simulating flow entering or exiting the computational domain to mimic propulsion effects have been implemented in an adaptive Cartesian simulation package. A robust iterative algorithm to control mass flow rate through an outflow boundary surface is presented, along with a formulation to explicitly specify mass flow rate through an inflow boundary surface. The boundary conditions have been applied within a mesh adaptation framework based on the method of adjoint-weighted residuals. This allows for proper adaptive mesh refinement when modeling propulsion systems.
• 05/03/2018 Towards an Immersed Boundary Method with Viscous Wall ModelChristoph Brehm, University of KentuckyImmersed boundary methods have drawn wide attention over the past few decades due to the fact that the mesh generation process can fully be automated independent of the complexity of the geometry. This presentation discusses different types of local wall modeling approaches that were proposed in previous research studies and combines them with an immersed boundary method. Standard sub-sonic turbulence modeling test cases, i.e., flow past the NACA0012 airfoil and flow over a bump in a channel, are used to test different implementations. A key focus of this presentation is to investigate the limitations of the different wall models, numerical implementation details of the immersed boundary method and the coupling effects.
• 04/26/2018 Active Aerodynamic Load Control for Multi-Element AirfoilsSheida Hosseini, University of California, DavisThis seminar will explore the feasibility of using nominally-orthogonal jets near the flap trailing edge as active aerodynamic load control on the two-element airfoil NLR7301 at a high-lift condition. We utilize Chimera Grid Tools to generate structured curvilinear overset grids, and the Reynolds-averaged Navier-Stokes solver OVERFLOW-2 to solve for the flow field around the airfoil. Results of this study show that large and controllable changes in aerodynamic performance can be achieved by relatively small active flow control inputs using the nominally-orthogonal jets.
• 04/19/2018 XCompute: Advanced Systems for Complex Science & EngineeringGraham J. Orr, Xplicit Computing, Inc.Conventional CAE is approaching complexity limits; trends in computing suggest a paradigm shift towards hierarchy, regularity, and modularity. In this webinar, a server-client architecture for heterogeneous numerical computing is introduced, enabling scalable technical work-flows and concurrent user access. A tree-like organization formalizes the project and tightens complex design iterations while leaving room for further sub-definition. Modern C/C++ meta-programming techniques are applied to numerical computing concepts, resulting in an extensible collaborative graphical simulation environment in about 50,000 lines of portable code.
• 04/05/2018 Interaction of Isotropic Turbulence with an Actuator DiskAditya Ghate, Stanford UniversityThe interaction of a dragging, fixed thrust coefficient actuator disk with decaying homogeneous isotropic turbulence (HIT) of varying spatial length scales and dissipation rates is studied using Large Eddy Simulation (LES). In the first half of the talk, the deformation of the inflow turbulence as it enters the core, and the wake shear layer turbulence are characterized in detail. The strong sensitivity of the shear layer entrainment to the integral length scale of the incident turbulence (as opposed to its “intensity”) is explained in terms of excitation of low Strouhal number Kelvin-Helmholtz wave packets using a space-time modal decomposition (SPOD) of the pressure field.
• 03/29/2018 Reduced-Order Modeling: Using Machine Learning to Enable Large-Scale Simulations for Many-Query ProblemsKevin Carlberg, Sandia National LaboratoriesThis talk will present several approaches that exploit simulation data and machine-learning techniques to overcome the high cost of large-scale simulations that render them impractical for many-query problems. Nonlinear model reduction methods that employ simulation data and subspace projection to reduce the dimensionality of nonlinear computational models will be introduced, as well as an adaptive-refinement method that incrementally increases the fidelity of the reduced-order model until it satisfies any prescribed error tolerance, and methods for data-driven error modeling.
• 03/22/2018 Airborne Science-Driven CFD of Small UAS: Scalable Airframe and Ice Accretion SimulationsRobert Comstock, Sean Lam, and Jared Sagaga, Student Interns, NASA Ames Research CenterIn the summer of 2017 a trio of interns commenced to investigate some science-driven questions for small unmanned aerial systems (UAS) that can be answered by computational fluid dynamics (CFD) approaches. This seminar summarizes three of the CFD projects that will support future Earth Science missions. The first part of this talk will discuss CFD simulation and initial tradeoff study of modular, scalable small UAS in this case using the example of a “FrankenRaven” that can be assembled into multiple configurations. The second part will investigate the ice accretion on small low-speed UAS at various flight and icing conditions by testing them in the Icing Research Tunnel (IRT) at NASA Glenn Research Center.
• 03/15/2018 A High Resolution Compact Scheme for Compressible Flows Involving Shocks and TurbulenceAkshay Subramaniam, Stanford UniversityThis seminar will present a new high-order weighted compact high resolution (WCHR) scheme based on the idea of weighted compact nonlinear schemes (WCNS’s) for shock capturing in compressible flows that has improved resolution properties compared to previous WCNS’s. Different test cases demonstrate the ability of this scheme to capture discontinuities in a robust and stable manner while also localizing the required numerical dissipation to regions with discontinuities and high wavenumber features and hence preserving smooth flow features better in comparison to WCNS’s.
• 03/13/2018 Weakly Non-Boussinesq Convection and Convective Overshooting in a Spherical ShellLydia Korre, University of California, Santa CruzThis seminar will discuss a study of Boussinesq convection in a weakly compressible gaseous spherical shell in order to model stellar convection zones, including 3D numerical simulations using the PARODY code for three different model setups. Additionally, a two-layered system that consists of a convectively stable region below an unstable one will also be discussed.
• 03/07/2018 Large-scale LES Analysis in Real Industrial Applications From the Historical Perspective of CFDKozo Fujii, Tokyo University of ScienceIn this seminar, we look back at CFD's remarkable progress over the last 30 years, with a brief discussion of aero-acoustic applications. A mechanism of flow separation control by DBD plasma actuators, based on a series of HPC simulations of the flows over airfoils, is also discussed. Guidelines are given on how to use this device efficiently for flow separation control, based on observations and post-analysis of simulation results.
• 02/22/2018 Near Lean Blowout Simulations of a Model Gas Turbine CombustorJeffrey Labahn, Stanford UniversityModern jet engines are designed to be highly efficient while limiting the amount of harmful emissions produced. We developed and applied state-of-the-art multi-physics computer simulations to investigate the behavior of new fuels and compare their performance to current jet fuels. We present an overview our recent work as part of the National Jet Fuel Combustion Program, including investigation of the importance of secondary droplet breakup and the impact of the initial droplet distribution on near lean blowout predictions.
• 02/13/2018 Launch Vehicle Aerodynamics Database Development for SLSDerek Dalle, Computational Aerosciences Branch, NASA Ames Research CenterLaunch vehicle aerodynamics requires analysis of flow speeds from zero to Mach 20 and altitudes from sea level to low Earth orbit. This talk gives an overview of how these pieces fit together for the Space Launch System (SLS) program, with a focus on key contributions of the NASA Ames SLS CFD Team: ascent aerodynamics and booster separation. The talk will also cover some interesting work, such as a technique to provide uncertainty for non-scalar databases such as aerodynamic line loads.
• 02/18/2018 Coupled Aero-Propulsive Design Optimization Of a Boundary Layer Ingestion Propulsor Justin Gray, Propulsion Systems Analysis Branch, NASA Glenn Research CenterAirframe-propulsion integration concepts that use boundary layer ingestion (BLI) have the potential to reduce aircraft fuel burn. NASA's STARC-ABL concept aircraft configuration offers the potential to reduce fuel burn by using an turbo-electric propulsion system with an aft-mounted, electrically driven BLI propulsor. To address the need for a more careful quantification of the aeropropulsive benefit of the STARC-ABL concept, we run CFD design optimizations based on a fully coupled aeropropulsive model. Results show that these optimizations are essential to evaluate current and future BLI concepts.
• 12/12/2017 Large-Scale Molecular-Level Simulations of Hydrodynamic Instabilities and Turbulence in Gases Michael Gallis and Steve Plimpton, Sandia National LaboratoriesIn this two part talk, we will first discuss the Direct Simulation Monte Carlo (DSMC) models and large-scale computing resources we have leveraged to simulate hydrodynamic instabilities (RM, RT) and turbulence in gases, highlighting our latest results. We will then talk about computational aspects of Sandia's SPARTA DSMC code, including features that allow it to run efficiently on large machines, as well as plans for future developments of interest to NASA.
• 10/31/2017 Implementation of a Body Force Model in OVERFLOW for Propulsor SimulationsDogus Akaydin, Science and Technology CorporationIn order to improve fuel efficiency of commercial airplanes, NASA pursues a variety of advanced airframe and propulsion aircraft concepts, such as boundary layer ingestion (BLI). This seminar will present an implementation of a recent propulsor model into NASA's workhorse CFD code OVERFLOW to improve modeling fidelity of aircraft concepts with BLI propulsors. This propulsor model estimates the forces imparted on the fluid by the blade camber surfaces as body force source terms in the momentum and energy equations over grids that represent the rotor and stator of a fan stage.
• 10/12/2017 Lattice Boltzmann and Navier-Stokes Cartesian CFD Approaches for Airframe Noise PredictionsMichael Barad, NASA Ames Research CenterLattice Boltzmann (LB) and compressible Navier-Stokes (NS) equations based computational fluid dynamics (CFD) approaches are compared for simulating airframe noise. Both LB and NS CFD approaches are implemented within the Launch Ascent and Vehicle Aerodynamics (LAVA) framework. Both schemes utilize the same underlying Cartesian structured mesh paradigm with provision for local adaptive grid refinement and sub-cycling in time. We choose a prototypical massively separated, wake-dominated flow ideally suited for Cartesian-grid based approaches in this study. The partially-dressed, cavity-closed nose landing gear (PDCC-NLG) noise problem from AIAA's Benchmark problems for Airframe Noise Computations (BANC) series of workshops.
• 10/05/2017 Ansys Discovery LiveMetin Ozen, OZEN Engineering Inc.This is a tool that is currently a Tech Preview, i.e., not a commercial release although customers are able to download and use it. Discovery Live is a brand new tool leveraging GPU technology to deliver instantaneous structural/fluid results with very little input from the user. The idea is to allow designers to quickly understand how changing the geometry or changing a boundary condition affects the stress or velocity or deformation. Discovery Live leverages the geometry modeling power of Ansys SpaceClaim and thus users are able to interactively modify the geometry. As soon as a particular modification is complete, the structural and/or fluid results will update instantaneously. Discovery Live is a new way of doing simulation that is far easier than anything before and should lead to a far greater democratization.
• 09/28/2017 Jet Noise Prediction Using Hybrid RANS/LES with Structured Overset GridsJeff Housman, NASA Ames Research CenterHybrid RANS/LES simulations using the structured overset grid approach and low-dissipative finite-difference method within the Launch Ascent and Vehicle Aerodynamics (LAVA) solver framework are presented for jet noise prediction. The simulations are part of a validation effort to demonstrate jet noise prediction capability, to assess noise characteristics of next generation quiet supersonic commercial jets. Results are compared with experimental data acquired in the Small Hot Jet Acoustic Rig in the Aeroacoustic Propulsion Laboratory at NASA Glenn Research Center. Details of the structured overset grids, numerical discretization, and turbulence model are presented. Near-field comparisons to PIV data and far-field comparisons to microphone data are discussed.
• 09/14/2017 CFD Analysis in Advance of the NASA Juncture Flow ExperimentHenry Lee, Science and Technology Corporation / NASA Ames Research CenterMultiple wing configurations were designed and evaluated using computational fluid dynamics (CFD), and a series of wind tunnel risk reduction tests were performed to further down-select the candidates for the final experiment. This talk focuses on the CFD analysis done in conjunction with the 6 percent scale risk reduction experiment performed in NASA Langley’s 14- by 22-Foot Subsonic Tunnel.
• 09/07/2017 Cart3D Simulations for the Second AIAA Sonic Boom Prediction WorkshopGeorge Anderson, Science and Technology Corporation / NASA Ames Research CenterThis seminar will present Cart3D results for the test cases prescribed in the Second AIAA Sonic Boom Prediction Workshop. The cases range in complexity from an axisymmetric body to a full low-boom aircraft configuration with a powered nacelle. The inviscid, embedded-boundary Cartesian-mesh flow solver Cart3D is used to compute “boom carpets”—pressure signatures at a range of specified distances and off-track angles.
• 08/29/2017 The Impact of Modern Multi-Disciplinary Simulation on Improving Aircraft System DesignDurrell Rittenberg, Siemens Industry SoftwareInnovations in the aerospace industry are transforming the very nature of air-transportation. Until recently, leveraging multi-disciplinary simulation early in the design process to improve performance was largely unfeasible. Due to rapid improvements in High-Performance Computing and modern simulation methods, organizations are now looking to simulation tools to drive innovation into the design process. But this kind of innovation is often difficult to implement and organizations struggle to realize the promise of multi-disciplinary simulation. This presentation will discuss how leading aerospace companies are realizing the benefits of simulation-driven design to improve performance and differentiate their products.
• 08/17/2017 Intelligent Light and the CFD 2030 VisionSteve M. Legensky and Brad J. Whitlock, Intelligent LightThis talk highlights recent activities at Intelligent Light that includes how to manage the massive data flows resulting from ensembles of unsteady CFD calculations, new tools that support engineering use of uncertainty quantification techniques and the latest HPC-FieldView software that combines the familiar interface of FieldView with the scalability of VisIt. Through the lens of post-processing and data analysis, we have gained a unique perspective on research and engineering use of CFD from the late 1980's through today. The talk touches on this history while giving examples of state-of-the-art petascale CFD and surveys the challenges that exascale computing is intended to address.
• 08/10/2017 High-Order Summation-By-Parts Operators on Unstructured GridsDavid Zingg, University of TorontoSummation-by-parts operators provide a promising option for high-order discretization of partial differential equations. Until recently, such operators were restricted to structured grids. In this seminar, extension of summation-by-parts operators to unstructured grids will be presented. A review of summation-by-parts concepts, including a generalized approach, will be provided. Similarities to and differences from finite-element methods will be described. Finally, opportunities for future research will be discussed.
• 08/08/2017 An Overview of the Advanced Air Transport Technology (AATT) ProjectJames Heidmann, NASA Glenn Research CenterThe Advanced Air Transport Technology (AATT) Project supports the exploration and development of safe and viable game-changing concepts, technologies, and tools to improve subsonic fixed-wing commercial transport vehicle and propulsion system energy efficiency, environmental compatibility, and economic impact for the nation. This presentation will provide context for AATT’s role within the NASA Aeronautics Research Mission Directorate, describe the current AATT research portfolio, and look ahead to challenges and opportunities within the project for fiscal year 2018 and beyond.
• 08/07/2017 Resonant Mode Control from Transonic to Hypersonic Boundary Layers Over Complex Wall ImpedanceCarlo Scalo, Purdue UniversityThe talk will discuss fundamental computational and physical aspects associated with transitional and turbulent boundary layer control over porous walls. The dynamics of waves propagating in the porous cavities will be analyzed via a novel inverse acoustic eigenvalue approach with focus on the characterization of the complex broadband surface impedance. Results from high-fidelity numerical simulations retaining full aeroacoustic coupling between the overlying flow and porous walls via imposition of time-domain impedance boundary conditions, or TD-IBC, will be presented.
• 07/27/2017 Damage from Hydrocode Simulations of Asteroid Airburst or ImpactsDarrel Robertson, STC/NASA Ames Research CenterIf an asteroid was the impact the Earth would it be more dangerous if it hit the land causing an earthquake, in a shallow sea or in a deep ocean where it can create a tsunami wave? This seminar covers work presented in May at the International Academy of Astronautics Planetary Defense Conference in Tokyo, Japan. A set of hydrocode simulations were conducted following the hypothetical scenario from the conference of a 100–250 meter diameter asteroid on a potential impact course with Earth.
• 07/20/2017 A Perspective on Transition Modeling in Computational Fluid DynamicsJim Coder, University of Tennessee, KnoxvilleThere is an ever-growing demand for laminar-turbulent transition modeling capabilities in production computational fluid dynamics (CFD) solvers, however evaluating some of the qualities of classical, non-CFD methods generally require non-local search and/or integration operations, which is incompatible with massive parallelization and arbitrary geometries. Instead, modeling transition using locally defined advection-diffusion-type PDEs similar to those used to model turbulence is more desirable, and enables compatibility with existing solver algorithms and parallelization strategies. An overview of several such transition models and their underlying physics will be presented, including the amplification factor transport model, developed by the author, that incorporates the eN method of linear stability theory in a CFD-compatible framework.
• 07/06/2017 Computational Modeling of Meteor-Generated Ground Pressure SignaturesMarian Nemec, Computational Aerosciences Branch, NASA Ames Research CenterThis seminar will present a thorough validation of a computational approach to predict infrasonic signatures of centimeter-sized meteoroids. This is the first direct comparison of computational results with well-calibrated observations that include trajectories, optical masses and ground pressure signatures. We assume that the energy deposition along the meteor trail is dominated by atmospheric drag and simulate a steady, inviscid flow of air in thermochemical equilibrium to compute a near-body pressure signature of the meteoroid.
• 06/28/2017 Computationally Efficient Transonic and Viscous Potential Flow Aero-Structural Method for Rapid Multidisciplinary Design Optimization of Aeroelastic Wing Shaping ControlEric Ting and Daniel Chaparro, Intelligent Systems Division, NASA Ames Research CenterTo capitalize on wing flexibility and address adverse aeroelastic concerns, mission adaptive wing technologies have been sought after, including the Variable Camber Continuous Trailing Edge Flap (VCCTEF), which is a novel, full span, multi-purpose wing shaping control technology capable of adaptive reconfiguration of wing shapes for improved aerodynamic efficiency. When implemented in an aero-structural framework, there is strong agreement between lift-to-drag ratios (L/D) from the transonic and viscous flow corrected potential flow solver and Reynolds Averaged Navier-Stokes (RANS) solutions provided by LAVA. Drag optimizations are conducted utilizing the rapid aero-structural tool examining different VCCTEF deflection profiles and configurations of inboard and outboard flaps.
• 06/14/2017 Virtual Reality 3D Design Collaboration OnlineAli Merchant, iQ3ConnectHuman beings are visual, immersive thinkers... but why don't we make products this way? When you and your team can interact hands-on with the design... walk around it with your feet instead of a mouse... only then will you see it the same way as customers. When your team members can see the product this way you can be sure that everyone shares the same vision, allowing more unified collaboration. iQ3 Virtual Reality Platform is the collaborative VR service for your CAD and simulation, making it as accessible as video conferencing. See how iQ3 can break down the barriers of understanding.
• 05/25/2017 Progress in Strand Mesh Generation and Domain Connectivity for Dual-Mesh CFD SimulationsJay Sitaraman, Parallel Geometric Algorithms, LLCThe strand grid approach is a flow solution method where a prismatic-like grid using "strands" is grown to a short distance from the body surface to capture the viscous boundary layer and the rest of the domain is covered using an adaptive Cartesian grid. This seminar will demonstrate algorithms developed for strand meshing and domain connectivity with applications that include the DLR-F6 fuselage, the UH-60A blackhawk and the NASA hi-lift CRM model, using a strand grid solver called mStrand.
• 05/18/2017 Navier-Stokes Simulation of UH-60A Rotor/Wake Interaction Using Adaptive Mesh RefinementNeal M. Chaderjian, NASA Advanced Supercomputing DivisionTime-dependent Navier-Stokes simulations have been carried out with the OVERFLOW CFD code for a flexible UH-60A Blackhawk helicopter rotor in forward flight. The numerical results presented in this seminar have very strong blade-wake interaction, including blade vortex interaction (BVI), and dynamic stall with BVI. These are two common conditions that occur as modern helicopter designs strive to achieve greater flight speeds and payloads. The numerical simulations utilize high-order spatial accuracy and a hybrid RANS/LES turbulence model.
• 05/11/2017 Laminar-Turbulent Boundary-Layer Transition on a Flared Cone at Mach 6Christoph Hader, University of ArizonaThis presentation will cover the flared cone geometry that was designed to observe natural transition in so-called quiet hypersonic wind tunnels, such as the Boeing/AFOSR Mach 6 Quiet Tunnel (BAM6QT) at Purdue University. This research investigates the cone model using Direct Numerical Simulations (DNS). The simulation results have exhibited streamwise streaks of high skin friction and of high heat transfer at the cone surface during the nonlinear transition stages.
• 05/02/2017 Simulations of Radiative Transfer in Combustion Systems and Developments of High-Order Spectral Harmonics MethodsWenjun Ge, University of California, MercedThis presentation will first discuss the physical nature of radiative transfer in combustion processes, which explains why it is challenging to design or identify appropriate radiation solvers for any specific size or type of flames. It will also describe the nongray treatment of combustion products by FSK spectral method and a recent implementation of a customized FSK look-up table, and present the recent developments and performances of high-order spherical harmonics methods showing their strengths and limitations.
• 04/27/2017 The Engineering Sketch Pad (ESP): Supporting Design Through AnalysisBob Haimes, Massachusetts Institute of TechnologyThis talk will discuss Computational Aircraft Prototype Syntheses (CAPS), a part of the Engineering Sketch Pad (ESP), which combines proven computational geometry, best-in-class meshing, and analyses model generation techniques into a complete browser-based, client-server environment that is accessible to the entire design team of an aerospace vehicle. CAPS links analysis and meshing disciplines to any ESP geometry model via dynamically-loadable Analysis Interface Module (AIM) plugins. This presentation describes the fundamental building blocks of ESP, as well as the paradigm shift of creating multi-disciplinary geometry for multi-fidelity design.
• 04/20/2017 New Capabilities in Version 7.0 of the Helios Rotorcraft Simulation CodeAndrew Wissink US Army Aviation Development DirectorateThis talk will cover new capabilities in the latest release of Helios, the Army's high-fidelity CFD/CSD rotorcraft simulation code, including: a new mStrand strand grid generation and solver; two new unstructured near-body solvers; specification of a body hierarchy with frames and motion definitions through updates to the MELODI interface; and a newly designed GUI. Example application of these capabilities will also be presented.
• 03/30/2017 PyTecplot and Tecplot 360 2017 R1: How to Enhance Visualization Productivity with PythonAlan Klug and John Goetz, TecplotPyTecplot, Tecplot 360's new scripting interface, aims to solve many of the problems engineers face when dealing with large-scale CFD post-processing. This talk will cover the high-level architecture of the PyTecplot package as well as a detailed presentation covering common tasks such as loading data, saving and presenting images. Current documentation and educational resources will be highlighted, followed by an overview of planned work and the direction PyTecplot will take in the coming year.
• 03/23/2017 The Continuous Adjoint Method for Multi-Fidelity Hypersonic Inlet DesignHeather Kline, Stanford UniversityA number of the challenges remaining in aerospacecraft design and simulation-based design techniques can be addressed by improving on methods of gradient computation, including gradient-based design and uncertainty quantification. This seminar will focus on developments towards generalizing a particular method of evaluating sensitivities and gradients (the continuous adjoint method) to a wider range of functions and multi-fidelity models.
• 03/14/2017 Computational Support for 9x7 Wind Tunnel Test of Sonic Boom Models with PlumesJames Jensen, NASA Ames Research CenterAn extensive wind tunnel test was conducted in February 2016 in the NASA Ames 9- by 7- Foot Supersonic Wind Tunnel to help address the nozzle jet effects on sonic boom. Five test models with a variety of shock generators of differing waveforms and strengths were tested with a convergent-divergent nozzle for a wide range of nozzle pressure ratios. The LAVA unstructured flow solver was used to generate first CFD comparisons with the new experimental database using best practice meshing and analysis techniques for sonic boom vehicle design for all five different configurations.
• 03/09/2017 Overset Mesh Generation for the High-Lift Common Research ModelWilliam Chan, NASA Ames Research CenterThis seminar will discuss structured overset meshes for the High-Lift Common Research Model (CRM) that were generated to support the first AIAA Geometry and Mesh Generation Workshop and the third AIAA High-Lift Prediction Workshop. Four grid systems at the course, medium, fine, and extra-fine grid resolutions have been created for a full flap gap case, and a grid system at the medium resolution has been created for a partially-sealed flap gap case. Best practices in domain decomposition, grid point distribution, mesh connectivity, and grid generation process management will also be discussed.
• 03/02/2017 Uncertainty Quantification Analysis of DNS Data with RANS-DNS SimulationsSvetlana V. Poroseva, University of New MexicoIn RANS-DNS simulations of incompressible turbulent flows, the Reynolds-averaged Navier-Stokes (RANS) equations are solved, with all terms but molecular diffusion being represented by the data from Direct Numerical Simulations (DNS). Results of RANS-DNS simulations conducted with four DNS datasets in planar wall-bounded flows will be presented and discussed. In particular, it will be shown that the results of RANS-DNS simulations are in a strong disagreement with the DNS profiles for velocity moments, and that the dominant uncertainty source in such simulations is the DNS data inaccuracies.
• 02/23/2017 An ODE-based Wall Model for Turbulent Flow SimulationsMichael J. Aftosmis, NASA Ames Research CenterWe present a new wall model to compute turbulent boundary layers using the RANS equations in high Reynolds number flows. The model solves a two-point boundary value problem for a coupled set of equations for the streamwise velocity and the turbulent viscosity. Since it includes both the pressure gradient and the momentum balance of the full Navier-Stokes system, the ODE is valid farther from the wall. We implement the model within a Cartesian cut cell method, and use one-dimensional linelets in each cut cell to avoid the excessive mesh refinement that would otherwise be needed. The linelets are coupled to the outer Cartesian grid in a fully conservative manner, with two-way interaction between the linelets and the background grid.
• 02/14/2017 Overset Grid Simulations for the 2nd AIAA Aeroelastic Prediction WorkshopJeffrey Housman, NASA Ames Research CenterComputational simulations for the 2nd AIAA Aeroelastic Prediction Workshop using the structured overset grid solver within the Launch Ascent and Vehicle Aerodynamics (LAVA) framework are presented. Three test cases from the workshop are considered: case (1a) steady-state transonic flow over the Benchmark Super Critical Wing (BSCW), case (1b) unsteady forced oscillation of the BSCW, and case (3a) unsteady transonic flow over the BSCW including shock/boundary-layer separation effects.
• 02/07/2017 Adjoint-based Aerodynamic and Aerostructural Optimization of Transport AircraftGaetan Kenway, University of MichiganThis talk will address the dual challenge of performing high-fidelity aerostructural optimization with a large number of design variables. The key enabling component is the coupled adjoint method allowing the use of efficient gradient-based optimization techniques. The main components of an aero-structural optimization framework will be discussed, including CFD solver, load and displacement transfer, structural solver, mesh deformation and geometric manipulation method.
• 01/31/2017 Wall-Modeled Large-Eddy Simulation of Separated FlowsFrancois Cadieux, STC/NASA Ames Research CenterThis seminar will discuss a newly proposed integral wall model for large-eddy simulation (LES) called iWMLES, which significantly relaxes the requirement of resolving the viscous sub-layer and aims to bring the cost of performing simulations of unsteady, separated flows at high Reynolds number within reach. The model has been validated for developing turbulent boundary layer flows and turbulent flow over an array of cubes.
• 01/26/2017 Dynamics of Turbulent Convection in Moderate-Mass StarsIrina N. Kitiashvili, Bay Area Environmental Research Institute (BAERI)This seminar will present results from 3D time-dependent radiative hydrodynamics models of stellar outer convection zones and atmospheres using the "StellarBox" code for several moderate-mass stars GFA spectral types including a case where the computational domain includes layer from the photosphere, convection zone, and transition to the radiative zone (overshoot layer), and will discuss applications of these simulations for explaining helioseismology results, studying dynamical properties of stars, and improving accuracy of exoplanet detection.
• 01/17/2017 Aircraft Propulsor Modeling and Design for Boundary Layer IngestionDavid K. Hall, Massachusetts Institute of TechnologyThis presentation describes a new conceptual framework for three-dimensional turbomachinery flow analysis and its use to assess fan stage attributes for mitigating the adverse effects of Boundary Layer Ingestion (BLI). The turbomachinery is modeled in CFD calculations using momentum and energy source distributions that are determined as a function of local flow conditions and an approximate blade geometry.
• 01/12/2017 Uncertainty Quantification in Multi-Phase Cloud Cavitation Collapse Using Multi-Level Monte CarloJonas Šukys, Computational Science & Engineering LabCloud cavitation collapse pertains to the erosion of liquid-fuel injectors, hydropower turbines, ship propellers, and is harnessed in shock wave lithotripsy. To assess the development of extreme pressure spots and other key quantities of interest for such systems, we performed numerical two-phase flow simulations of cloud cavitation collapse containing up to 50,000 bubbles using up to 1 trillion domain discretization cells. To quantify the propagation of aforementioned uncertainties in collapsing cavity clouds under uncertain configurations, we employ a novel non-intrusive multi-level Monte Carlo methodology, aiming to accelerate the plain Monte Carlo sampling.
• 12/15/2016 Performance Advantages of a Data Centric Computer ArchitectureKen Jacobsen, EMU TechnologyThere is growing evidence that traditional computer architectures do not handle applications well where the data is not cache-friendly, such as sparse matrix operation, data analytics, machine learning and graph analysis. This is partly due to memory access characteristics, and partly how accesses to remote memory are handled for many core machine implementations. This talk will introduce a new highly-scalable PGAS architecture that can scale to very large sizes using a shared memory programming model, and does so relatively invisibly to the programmer. In this architecture, the program thread migrates to the data, and data never moves, which can result in dramatic performance improvements.
• 11/10/2016 A High-Order Accurate Particle-in-Cell Method for Vlasov-Poisson Problems Over Long Time IntegrationsAndrew Myers, Lawrence Berkeley National LaboratoryThe Vlasov-Poisson system of equations is used to model collisionless fluid flows in both plasma physics and cosmology. Particle methods—especially the popular Particle-in-Cell technique—are a common approach to obtaining numerical solutions to this system. This talk describes a new Particle-in-Cell method that is 4th-order accurate in both space and time, and uses a 6th-order phase-space remapping technique to control particle noise at late times.
• 11/03/2016 Numerical Investigation of Shock Instabilities in Noble GasesMichael Kapper, Austrian Space Research InstituteThis presentation will discuss work being done to simulate details of a multi-dimensional shock structure through direct simulation. The numerical capability is built around a third-order algorithm for solving the transport equations of plasma under highly non-equilibrium conditions. Recent extensions of the models including MHD effects will also be highlighted.
• 10/27/2016 The Parallel Research Kernels, a Tool for Parallel Systems Investigations Part IIRob Van Der Wijngaart, Intel CorporationThis presentation will discuss Parallel Research Kernels (PRK), a suite of simple, parameterized workloads that can be used to assess various aspects of parallel computer systems, ranging from compilers to common runtimes like MPI and OpenMP, UPC, etc. Two new PRKs, PIC and AMR, that proxy the two main patterns of load imbalance in HPC will be introduced. Important difficulties in developing such kernels are the need for simplicity and compactness, and the need for analytical solutions. This seminar will show how the new kernels satisfy these requirements and the salient performance results for the reference implementations.
• 10/20/2016 Parallel Fast Sweeping: Algorithms and ApplicationsMiles Detrixhe, University of California Santa BarbaraThe Fast Sweeping Method (FSM) is an efficient iterative finite-difference method for solving a range of nonlinear static (time-independent) Hamilton-Jacobi equations. The focus of this talk is the family of parallel FSMs which take advantage of modern high performance computing technology (HPC), and algorithms for uniform Cartesian meshes designed for both shared and distributed parallel systems will be discussed. The graph theoretic approach for generalizing the parallel scheme to arbitrary grids including adaptive tree based and triangulated meshes will also be presented.
• 10/13/2016 The Parallel Research Kernels, a Tool for Parallel Systems Investigations Part IRob Van Der Wijngaart, Intel CorporationThis presentation will give an overview of the philosophy behind Parallel Research Kernels (PRK), a suite of simple, parameterized workloads that can be used to assess various aspects of parallel computer systems, ranging from compilers to common runtimes like MPI and OpenMP, UPC, SHMEM, Charm++, Grappa, Legion, OCR, HPX, and Fine-Grain MPI. Individual kernels will be introduced, and usage models and perfomance results for several of the most important kernels will be shown.
• 10/03/2016 Spectral Analysis of the Acoustic Near Field of a Solid Propellant RocketChristopher Tam, Florida State UniversityThis talk presents results of an analysis of the measured spectrum data published recently in the International Journal of Aeroacoustics. The primary objective is to determine the dominant noise components in the near field of the rocket plume. Two dominant noise components are found, and both are generated by the turbulence of the jet flow. In addition, a model of the spatial distribution of the sources of the two dominant noise components is proposed.
• 09/27/2016 Applications of the DSMC Simulator SPARTA for Ablation ModelingArnaud Borner, University of Illinois Urbana-Champaign/NASA Ames Research CenterThis presentation will discuss how the direct simulation Monte Carlo (DSMC) simulator SPARTA is used to compute permeability of several TPS materials such as virgin FiberForm, oxidized FiberForm, Morgan carbon felt, and Calcarb to high temperature gases. The actual porous geometry of the materials is digitized using X-ray micro-tomography and the code is modified to read in micro-tomography data as input geometries. Numerical results at various pressure and Knudsen number are compared with experimental data.
• 09/22/2016 Tsunami Generation from Asteroid Airburst and Ocean ImpactDarrel Robertson, Science &Technology Corporation (STC)This seminar will present simulations of asteroid induced tsunami waves from both airburst and ocean impact, using the ALE3D hydrocode, and their propagation. The goal of this work is to help determine the threat of asteroids entering Earth's atmosphere over the deep ocean, by examining the tsunami creation and possible shielding effects of the continental shelf.
• 09/12/2016 The Need for Well-Factored Dynamic Parallel Programming Systems, and Why Charm++ is a Good ChoicePhil Miller, Ph.D. Candidate, University of Illinois at Urbana-ChampaignCurrent and upcoming CSE applications present numerous sources of dynamic variation and adaptive behavior. These include multi-physics coupling, simulation-domain refinement in space and time, mixed or adjustable numerical precision, and iterative methods. This talk will focus on a dynamic parallel programming system, Charm++, which has evolved hand-in-hand with applications running at the largest scales over its 25 year history. The design of some of the current applications built on it will be described, as well as how the underlying design philosophy and runtime system support have allowed them to reach full-machine scales.
• 09/08/2016 An Immersed Boundary Method for Solving the Compressible Navier-Stokes Equations with Fluid-Structure InteractionMichael Barad, NASA Ames Research CenterThis presentation will discuss the underlying immersed boundary method using NASA's LAVA solver framework to account for all aspects that are involved for fluid-structure interaction simulations, such as fast geometry queries and stencil computations, the treatment of freshly cleared cells, and the coupling of the computational fluid dynamics solver with a linear structural finite element method. This approach is validated for moving boundary problems with prescribed body motion and fully coupled fluid-structure interaction problems in 2D and 3D.
• 09/01/2016 Shock-capturing Methods for High-Order Discontinuous Galerkin SchemesYu Lv, Stanford UniversityThis talk discusses recent developments of two artificial-viscosity (AV) formulations for high-order discontinuous Galerkin schemes that are suited for implicit and explicit numerical predictions. For explicit calculations, the design of the AV scheme is guided by the CFL stability constraint; while for implicit and time-dependent simulations, the AV scheme is designed to be able to achieve machine-zero solution-residuals. The discussion also covers the shock-detector based on an entropy-residual function, which forms another key ingredient of the new shock-capturing capability.
• 08/25/2016 Unstructured Grid Adaptation: Status, Potential Impacts, and Recommended Investments Toward CFD Vision 2030Mike Park, NASA Langley Research CenterThis seminar will discuss a computational fluid dynamics (CFD) vision study, which illustrates the current state of CFD capability and capacity. The study also forecasts the potential impact of bottlenecks caused by high-end computing environments, and presents a roadmap and a forecast for the next fifteen years with recommended investments specific to mesh adaptation and impact with other aspects of the CFD process. A strategy to diffuse grid adaptation technology into CFD workflows will also be presented.
• 08/18/2016 Open Rotor Computational Aeroacoustic Analysis with an Immersed Boundary MethodMichael Barad, NASA Ames Research CenterReliable noise prediction capabilities are essential to enable novel fuel efficient open rotor designs that can meet the community and cabin noise standards. Toward this end, Navier-Stokes based immersed boundary methods (IBM) have reached a level of maturity where more and more complex flow problems can be tackled with this approach. The Launch Ascent and Vehicle Aerodynamics (LAVA) structured Cartesian higher-order IBM methodologies for this moving boundary problem are discussed.
• 07/18/2016 Algorithms for Tangent and Adjoint Sensitivity Analysis of Chaotic Flow SimulationsQiqi Wang, Massachusetts Institute of TechnologyIt has been found that traditional algorithms for sensitivity analysis, either in its tangent or adjoint forms, may diverge exponentially, at a rate corresponding to the leading Lyapunov exponent of the chaotic simulation. A new algorithm has been developed to overcome this issue. The algorithm, based on the Least Squares Shadowing formulation, finds a non-diverging solution of the linearized governing equation. This presentation will share the recent experience of applying this algorithm to several flow simulations.
• 07/14/2016 Stabilization of Finite-Element High-Order Methods with Fourier Spectral Filters: Surviving High-Re, High-Ma flows, and Coarse GridsManuel R. López Morales, Northrop GrummanThis presentation describes the implementation of the Local Fourier-spectral (LFS) filters, developed by Asthana and the author, in HiFiLES, an open-source, high-order, Navier-Stokes solver for unstructured grids, and shows the results of high-Re simulations in coarse, unstructured 2D meshes. The simulations demonstrate the potential for LFS filters to stabilize high-order simulations under extreme conditions: very coarse grids, high-Re, high-Ma, and very low-Ma. A formulation of the LFS filters for a general high-order polygonal (2D) or polyhedral (3D) elements will also be presented.
• 07/07/2016 A Novel Approach for Shock Capturing in Unstructured High-Order MethodsAbhishek Sheshadri, Stanford UniversityHigh-order methods have shown great potential for increased efficiency for vortex dominated flows on account of their lower numerical dissipation. But a direct consequence of this reduced dissipation is their increased susceptibility to instabilities. Instabilities arising due to shocks in compressible flows have been investigated and a robust and efficient shock capturing strategy along with a novel shock detection mechanism inspired by image edge-detection has been proposed. The strategy is capable of sub-cell shock capturing on general unstructured grids and is applicable to any non-linear PDE.
• 07/05/2016 Computation of Turbulent Flow in a Rotating Pipe Using Standard Eddy-Viscosity Models and an Elliptic Blending Reynolds Stress ModelNeil Ashton, University of OxfordThis presentation will examine flow through a axially rotating pipe using the open-source code OpenFOAM for both standard eddy-viscosity models (Spalart-Allmaras & k – ω SST) and a low-Reynolds number Elliptic Blending Reynolds Stress Model with a homogenous turbulent dissipation rate equation, with the purpose of developing a new test-case for the NASA Turbulence Modelling Resource website to validate/verify turbulence models for a rotating flow. In addition to work on the rotating pipe case, a number of verification test cases were simulated to verify the implementation of the standard SA and SST models in OpenFOAM.
• 06/30/2016 Large-Eddy Simulation of Separated Flows Using a New Integral Wall ModelFrancois Cadieux, Johns Hopkins UniversityWall-resolving large-eddy simulation (LES) can accurately recover experimental and time-averaged direct numerical simulation results for many separated flows if interesting for engineering applications, but they are limited to moderate Reynolds numbers due to the strong requirement of resolving the viscous sub-layer. Hybrid RANS-LES methods must be employed to resolve simulations of high Reynolds number flows, however typical hybrid RANS-LES methods require very find mesh spacing to reliably capture separation and reattachment. This seminar will discuss a newly proposed integral wall model for LES (iWMLES) which addresses these issues through the addition of non-equilibrium terms in an integral version of the momentum equation.
• 05/31/2016 PyFR: High-Order Accurate Cross-Platform Petascale Computational Fluid Dynamics with PythonFreddie Witherden, Stanford University; Peter Vincent, Imperial College LondonThis talk will present PyFR, an open-source Python based framework for solving advection-diffusion type problems using the FR approach. The framework is designed to solve a range of governing systems on mixed unstructured grids containing various element types. The latest release of PyFR is able to solve the compressible Euler and Navier-Stokes equations on grids of quadrilateral and triangular elements in two dimensions, and hexahedral, tetrahedral, prismatic, and pyramidal elements in three dimensions, targeting clusters of multi-core CPUs, GPUs, Intel Xeon Phis, and heterogeneous mixtures thereof.
• 05/25/2016 Large-Eddy Simulations of Wall Bounded Turbulent FlowRavi Samtaney, The King Abdullah University of Science and Technology (KAUST)This seminar will present recent progress on wall-modeled large-eddy simulation (LES) of wall bounded turbulent flows. Five flow configurations are examined in detail, using extensions to the wall model, which include relaxation of the log-law assumption, extension into a two-dimensional wall model, and reformulation in generalized curvilinear coordinates.
• 05/10/2016 Recent Advances of the Lattice-Boltzmann Method for the Simulation of Transonic FlowsSwen Noelting, Exa CorporationThis seminar will present an extension of the Lattice Boltzmann Method (LBM) to transonic and supersonic flow speeds in the PowerFLOW code. LBM has emerged as a serious alternative to traditional Navier Stokes based CFD codes, in particular for the simulation of unsteady flows over highly complex geometries. A brief review of aerospace application examples of LBM, including airframe noise, high-lift aerodynamics and flow over iced airfoils, will be included in the presentation.
• 05/03/2016 Recent Experiences of Modeled-Stress Depletion Using DDES and IDDES for the 30P30N Three-Element AirfoilNeil Ashton, University of OxfordThis talk will focus on recent work for the BANC III workshop using the 30P30N three-element airfoil. DDES & IDDES simulations were conducted using both multi-block structured grids and unstructured grids using a commercial unstructured code. During the course of this work, problems were encountered with the boundary layer shielding functions of the DDES/IDDES models when the near-wall grid was refined. This led to grid-induced separation (GIS) and spurious noise which compromised the accuracy of the simulations.
• 04/28/2016 Helios Prediction of BVI Loading and Rotor Wakes of HART II RotorBuvana Jayaraman, Science and Technology CorporationThis seminar will present a comparison of the near-body solvers in the high-fidelity rotorocraft simulation code HPCMP CREATETM-AV Helios. The HART II(Higher-harmonic Aeroacoustic Rotor Test II) rotor test case was used to understand the effect of the near-body solvers on the prediction of rotor wakes and BVI (Blade Vortex Interaction). Earlier efforts used the unstructured solver NSU3D and the structured solver OVERFLOW, and recently the NASA FUN3D unstructured solver was integrated into Helios and validated for the HART II baseline case.
• 04/19/2016 Solution Algorithm on Unstructured Grids Using Hamiltonian Paths and Strand GridsJay Sitaraman, Parallel Geometric Algorithms, LLCAn approach for achieving line-structures in purely unstructured grids is presented in two and three dimensions. The method entails the identification of Hamiltonian paths created by quadrilateral subdivision of unstructured meshes to represent two distinct surface coordinate directions and strand grids to represent the wall normal direction. The Hamiltonian path based solver (HAMSTR) developed as part of this work is expected to become one of the near-body solvers in the Helios framework.
• 04/14/2016 Simulation of Air-Burst Generated Tsunamis Using GeoclawMarsha Berger, Courant Institute of Mathematical SciencesStrong blast waves from meteor airbursts can produce tsunamis. This seminar will present simulations for a range of conditions using the GeoClaw software package, an adaptive finite volume package for geophysical flows that solves the depth-averaged shallow water equations to model flows with bathymetry. Validation for earthquake-generated tsunamis will be discussed, and the modifications needed to study tsunamis generated from airbursts will be presented.
• 04/05/2016 Numerical Properties and GPU Implementation of a High Order Finite Volume SchemeJean-Marie Le Gouez, The French Aerospace Lab ONERAThis seminar will present the main features of a spatially high-order finite volume scheme for compressible fluid flows, based on a polynomial reconstruction by weighted least squares of conservative variable or flux densities fields only known from their cell averages. Use of an optimized multi-GPU version of the code is discussed, as well as a derived version being developed to deploy advanced features such as dynamical zonal refinement on octree-type embedded grid systems.
• 03/29/2016 Maneuvering Rotorcraft Simulations Using CREATE A/V HeliosBeatrice Roget, Science & Technology Corporation/NASA Ames Research CenterCREATE A/V Helios is a rotary-wing computational aeromechanics simulation frame-work that integrates high-fidelity computational fluid dynamics (CFD) with rotorcraft comprehensive analysis (CA). This presentation documents new code developments that enable simulation of generic flexible multi-body problems. These new capabilities are demonstrated through two test cases: a maneuvering rotorcraft with elastic deformations computed via CFD/CA coupling and a rotor equipped with trailing-edge flaps, with both flap deflections and blade/flap elastic deformations prescribed.
• 03/16/2016 Investigation on Airframe Noise Due to Flap Side Edge and Its ReductionMitsuhiro Murayama, Japan Aerospace Exploration Agency (JAXA)This presentation will focus on the effect of variations in the flap side edge shape on both the flowfield and the far-field noise, which results from unsteady fluctuations associated with instabilities of the separated flow around the side-edge of flap and near the gap between the main wing and the flap. Several flap side-edge configurations are investigated as potential means for suitable alterations to the unsteady fluctuations.
• 03/08/2016 Development and Validation of a Multi-Strand Solver for Complex Aerodynamic FlowsVinod Lakshminarayan, Science & Technology Corporation (STC)The strand grid approach is a flow solution method where a prismatic-like grid using "strands" is grown to a short distance from the body surface to capture the viscous boundary layer and the rest of the domain is covered using an adaptive Cartesian grid. The approach offers several advantages in terms of nearly automatic grid generation as well as the ability to implement fast and efficient flow solvers. This talk will provide an overview of a recently developed multi-strand solver called mStrand, which will be part of the Army's high-fidelity CFD/CSD rotorcraft simulation framework Helios.
• 03/03/2016 Overcoming the I/O Bottleneck Using Sub-Zone Load on Demand (SZL)Scott Imlay and Scott Fowler, Tecplot Inc.Disk I/O performance is not keeping up with the growth in computational fluid dynamics (CFD) grid size. The disk, therefore, has become the limiting factor in CFD visualization and post-processing speed. Sub-Zone Load (SZL) technology has been developed to overcome this bottleneck. This talk will present the motivations and technology behind SZL. It will also offer techniques for converting your data to SZL format, including how to write SZL, in parallel, directly from a solver using the TECIO-MPI library.
• 02/23/2016 Recent Advancements in the Helios Rotorcraft Simulation CodeAndrew Wissink, U.S. Army Aviation Development Directorate (AFDD)This talk will discuss recent advancements in the Helios code, the Army's high-fidelity CFD/CSD rotorcraft simulation code. These include a new implicit off body Cartesian solver to support both steady solutions and time-accurate RANS/DES in the wake, a new body hierarchy formulation to support coupled wing/rotor aeroelastics and maneuvering flight, a new strand-based near-body solver intended to support enhanced automation and accuracy, and the inclusion of two new unstructured near-body solvers—FUN3D from NASA and kCFD from the CREATE-AV Kestrel team.
• 02/16/2016 Boundary Condition Measurements in Wind TunnelsJames Bell, NASA Ames Research CenterThis presentation will describe the Aeronautics Evaluation and Test Capabilities (AETC) project's role in wind tunnel test technology and AETC’s current ideas about improving boundary condition measurements. The intent of this discussion is to solicit the CFD community’s advice in several areas, specifically the most important boundary condition measurements to obtain, the required accuracy for such measurements, and the most useful facilities to begin work in.
• 02/09/2016 Large Eddy Simulation of Airfoil Self-NoiseJoseph George Kocheemoolayils, Ph.D. Candidate, Stanford UniversityWhile significant strides have been made towards using large eddy simulations (LES) for predicting airfoil self-noise, they have been largely restricted to canonical configuration at low Reynolds numbers. This seminar will summarize the progress made towards extending the scope of LES-based predictions to full-scale Reynolds numbers and non-cannonical configurations, such as noise generated by flow past an airfoil in the near-stall and post-stall regimes.
• 02/04/2016 Numerical Simulation of Bolide Entry with Ground Footprint PredictionMichael J. Aftosmis, NASA Ames Research CenterThis seminar will discuss the development of a new technique for meteoroid airburst modeling based upon conservation analysis for the deposition of mass, momentum and energy. These sources can then used to drive simulations of blast propagation using a fully-conservative, finite-volume solver on a multilevel Cartesian mesh. A detailed reconstruction of the 2013 Chelyabinsk meteor provided additional validation. Further investigations that examined the impact of simplification to modeling using a line-source blast model and a static spherical charge will also be discussed.
• 01/29/2016 Scattering of Aerodynamically Induced Noise and Nonlinear Sound PropagationSeongkyu Lee, University of CaliforniaThis seminar presents two topics about theoretical and computational aeroacoustics: acoustic scattering and nonlinear sound propagation. Aerodynamically induced noise is scattered by neighboring surfaces, resulting in modifying the amplitude and directivity of sound energy. A new time-domain acoustic scattering solver and analytic formulations of the pressure gradient, a new frequency domain algorithm of the Burgers equation, and applications of the method to sonic boom, jet noise, helicopter noise are presented.
• 01/19/2016 Inviscid and Viscous CFD Analysis of Booster Separation for the Space Launch System VehicleDerek Dalle, STC / NASA Ames Research CenterAs part of the effort to certify that the separation of the solid rocket boosters from the Space Launch System will be successful, a team of NASA engineers was tasked with developing an aerodynamic database to cover every possible orientation of the boosters and core for use in a detailed Monte Carlo trajectory simulation. This presentation will discuss an aerodynamic database built using 25,000 Cart3D simulations and 300 OVERFLOW solutions.
• 01/14/2016 Simulation Enabled Discoveries: Examples from MHD and TurbulenceRavi Samtaney, The King Abdullah University of Science and TechnologyComputation has emerged as the indispensable third leg of scientific discovery along with the traditional two branches of theory and experiment. This talk will discuss some case studies from magnetohydrodynamics (MHD) and fluid turbulence, including magnetic suppression of the Richtmyer-Meshkov instability, magnetic reconnection, and the question of whether the mean velocity profile in a wall-bounded turbulence obeys a log-law or a power-law.
• 01/11/2016 A Dissipative Filter for DG Discretizations with Sub-cell Discontinuity ResolutionJohn Ekaterinaris, Embry-Riddle Aeronautical UniversityThis presentation will discuss a dissipative filter being adapted to the finite element context of DG discretizations. The filter operator is constructed in the canonical computational domain for the standard cubical element where it can be applied in a direction per direction basis, and then extended for all element types in unstructured meshes using collapsed coordinate transformations. The performance of the proposed dissipative mechanism is demonstrated and evaluated for different orders of expansions for one-dimensional and multidimensional problems with exact solutions.
• 12/10/2015 Numerical Investigation of Flow Phenomena in a Planar Expansion-Deflection NozzleGerrit Stich, University of StuttgartReducing the mass of a launcher's upper stage results directly in a higher payload capability. The German Aerospace Center is reevaluating an expansion deflection nozzle design from the 60s and 70s, which shows payload gain compared to a classical design. Knowledge of tools used for simulating the nozzle’s complex flowfield is critical for for validating model prediction capabilities and reliability.
• 12/08/2015 Turbulence Closure for Static and Dynamic Stall in the Transitional RegimeJoachim Hodara, Ph.D. candidate, The Georgia Institute of TechnologyThis presentation will discuss work which combines state-of-the-art hybrid RANS-LES turbulence closures and the correlation-based transition model of Langtry and Menter to tackle massively separated flows in the transitional flow region. This combined approach is capable of accurately predicting the features in these highly complex unsteady turbulent flows at a reasonable computational cost, and will be applied to the study of wings in the reverse flow regime.
• 11/12/2015 Computationally Efficient Algorithms for Flexible Multibody Dynamics SimulationsArun Banerjee, Retired Research ScientistThis presentation will cover recent developments in flexible multibody dynamics applications and analysis. While classical analytical methods to derive motion equations have been used since the beginning of the Space Age, there has been a revolution in the field in the last thirty years. For flexible bodies, a recursive formulation of the method leads to block-diagonal matrix differential equations. Errors of premature linearization with use of vibration mode coordinates, pervasive in the literature of the seventies, have also been eliminated by incorporating motion-induced geometric stiffness of structures.
• 11/03/2015 Solar Cycle Prediction and Reconstruction Using Spherical Advective Magnetic Flux Transport CodesDavid Hathaway, NASA Ames Research CenterThis presentation will discuss modeling the surface magnetic flux transport of the Sun's polar fields in detail using observed flows. These surface flux transport codes can also be used to predict the strength of the polar fields years before the end of a sunspot cycle and thus provide an earlier prediction for the strength of the next cycle. The limits of these predictions will be examined by reconstructing the sun’s magnetic field in previous cycles with spherical, 2D advective flux transport codes.
• 10/29/2015 Living With a Star: Science That Matters to PeopleMadhulika Guhathakurta, NASA Ames Research CenterModern society has come to depend on technologies sensitive to solar radiation and geomagnetic storms. Particularly vulnerable are intercontinental power grids, interplanetary robotic and human exploration, satellite operations and communications, and GPS navigation. Both short- and long-term forecasting models are urgently needed to mitigate the effects of solar storms and to anticipate their collective impact on aviation, astronaut safety, terrestrial climate and others. Work on space weather specification, modeling, and forecasting has great societal benefit: It is basic research with a high public purpose and the stated goal of LWS/ILWS is to achieve the Sun-Earth, Sun-Planet system understanding.
• 10/15/2015 Viscous Flow Simulations for Static Aeroelastic Analysis of a Wing at High-Lift ConditionsDogus Akaydin, STC/NASA Ames Research CenterThis seminar will present a static aeroelastic analysis of a wind tunnel test model of a wing in high-lift configuration using a viscous flow simulation code. The model wing was tailored to deform during the tests by amounts similar to a composite airliner wing in high-lift conditions. This required use of a viscous flow analysis to predict the lift coefficient of the deformed wing accurately. Our results indicate that the angle of attack of wing sections along the span decrease due to the induced washout deformation when the wing is aerodynamically loaded.
• 10/05/2015 Higher-Order Simulations of Flapping-Wing and Blade Aerodynamics Using Lattice Boltzmann MethodAlex Povitsky, University of AkronThis seminar will present a numerical model of aerodynamics of flapping wing in generalized pitching motion that has been developed based on the high-order compact approximation of derivatives in Navier-Stokes equations, non-inertial coordinate system attached to the moving wing, and carefully tuned non-uniform grid. The computational approach to modeling flapping blades in confined space is based on a novel particle-based kinetic Lattice Boltzmann method.
• 09/29/2015 Shape Optimization in Adaptive Search SpacesGeorge Anderson, Stanford UniversityThis presentation will discuss the development of a system for automatically adapting the shape parameterization to efficiently solve a given problem, instead of using a fixed, designer-constructed parameterization. In this approach, optimization begins with an small, naive initial set of design variables, which is then adaptively refined to enable the discovery of progressively superior designs. Our adaptation refinement indicator is driven by adjoint-based sensitivity information and by approximate Hessian information extracted from a quasi-Newton optimization process. We show that this system can autonomously discover parameters sufficient to solve two inverse design problems.
• 09/22/2015 The QuakeFinder Earthquake Forecasting Technology—A Signal Processing ProblemTom Bleier, QuakeFinderThis presentation will discuss large, complex statistical models of earthquakes that are currently being refined to attempt to predict the probability of major seismic events decades in advance. QuakeFinder, a research and development effort at Stellar Solutions, Inc., has attempted to capture and characterize changes in the Earth's magnetic signals near the epicenter of earthquakes weeks before the seismic event. The team has deployed sensors along fault lines in numerous countries in order to collect over 65 TB of data on these electromagnetic pulses, to help develop a signal processing algorithm capable of differentiating the earthquake pulse from man-made "noise."
• 09/17/2015 The Influence of Mesh Characteristics on External Airflow CFD Simulations of the DrivAer ModelPravin Peddiraju, BETA CAE SystemsDue to the reliance on computational fluid dynamics (CFD) in the design process within high tech industries, there is always a need to validate CFD simulation results with experiments for realistic models and thereby develop best practices for performing numerical simulations. This study explores a comparison of simulation results with experimental data for the DrivAer model, representative detailed automotive geometry. A variety of meshes that differ in quality, density, and the type of elements are generated using the commercial pre-processor ANSA, and their effect on the solution convergence and accuracy is thoroughly examined.
• 09/15/2015 Progress in Both All Mach Number Flow and Well-Balanced Methods for the Compressible Euler EquationsChristian Klingenberg, University of WuerzburgMany astrophysical systems feature flows are modeled by the multi-dimensional Euler equations. We discuss two aspects. First for the homogeneous Euler equations we look at flow in the low Mach number regime. We demonstrate that our new method is capable of representing flows down to Mach numbers of 10e-10. Second for the Euler equations with gravity we seek well-balanced methods. We describe a numerical discretization of the compressible Euler equations with a gravitational potential. We present a well-balanced method, for which we can ensure robustness, accuracy and stability, since it satisfies discrete entropy inequalities.
• 09/08/2015 CFD and EFD in the Design Process of Fans and BlowersPhilipp Epple, Coburg University of Applied SciencesThis presentation will discuss the importance of combining computational fluid dynamics (CFD) simulations with experimental fluid dynamics (EFD) tests in the design and evaluation of fans and blowers in turbomachines. Details on the differences and advantages of each tool in the design process will be given and illustrated with several real world examples worked out in detail.
• 08/27/2015 A Brief Study of the Effect of Rigid Swept Surface Waves on Turbulent DragMarie Denison, National Institute of Aerospace (NAI) / Science and Technology Corporation (STC)This presentation will explore the effect of swept wavy surfaces on skin friction and pressure drag by experiments and Direct Numerical Simulations (DNS). Plates with shallow and deep wave patterns were rapid-prototyped and tested using a drag balance in the 7x11 inch Low-Speed Wind Tunnel at the NASA Langley Research Center. The shortcomings of the linear model used for the estimation of the spanwise shear stress and drag are discussed.
• 08/20/2015 Noise Characteristics of a Four-Jet Impingement Device Inside a Broadband Engine Noise SimulatorChristoph Brehm, NASA Ames Research CenterThis presentation will cover the noise generation mechanisms for four directly impinging supersonic jets, which are investigated employing implicit large eddy simulations with a higher-order accurate weighted essentially non-oscillatory shock-capturing scheme. Impinging jet devices are often used as an experimental apparatus to emulate a broadband noise source. Although such devices have been used in many experiments, a detailed investigation of the noise generation mechanisms has not been conducted before.
• 08/13/2015 Developments in Efficient Mesh Connectivity for Overset GridsWilliam M. Chan, NASA Ames Research CenterAn automatic and efficient method to determine appropriate hole cuts based on distances to the wall and donor stencil maps for overset grids is presented. A new robust procedure was developed to create a closed surface triangulation representation of each geometric component for accurate determination of the minimum hole. Software features and OpenMP parallelization scaling issues are also discussed.
• 08/03/2015 Summary and Statistical Analysis of the First AIAA Sonic Boom Prediction WorkshopMike Park, NASA Langley Research CenterThis seminar will summarize work presented at the First AIAA Sonic Boom Workshop held in conjunction with AIAA SciTech 2014, focusing on near-field pressure signatures extracted from computational fluid dynamics solutions gathered from nineteen participants representing three countries. Understanding the sources of the variation observed at the workshop is critical to ongoing efforts to further the state-of-the-art in low boom configuration analysis and design.
• 07/30/2015 Discrete Exterior Calculus Discretization of the Incompressible Navier-Stokes EquationsRavi Samtaney, King Abdullah University of Science and Technology (KAUST)This seminar will discuss a conservative discretization of Navier-Stokes equations on simplicial meshes developed based on discrete exterior calculus (DEC). The governing equations are first rewritten using the exterior calculus notation, replacing vector calculus differential operators by the exterior derivative, Hodge star and wedge product operators. The discretization is then carried out by substituting the corresponding discrete operators based on the DEC framework. Numerical tests will be presented for flows on flat and curved 2D domains.
• 07/16/2015 DNS and LES of Stabilization and Instabilities in Rocket EnginesThierry Poinsot, The French National Center for Scientific Research (CNRS)This talk will present some recent developments in two areas: multidimensional summation-by-parts (SBP) operators on simplices, and exploratory aerodynamic shape optimization. A definition is given for multidimensional SBP finite-difference operators that extends the classical one-dimensional definition. In the second portion of the talk, exploratory aerodynamic shape optimization is applied to a regional-class blended-wing body (BWB) aircraft configuration.
• 07/14/2015 Developments and Opportunities Related to High-Order Methods and Aerodynamic Shape OptimizationDavid Zingg, University of TorontoThis talk will present some recent developments in two areas: multidimensional summation-by-parts (SBP) operators on simplices, and exploratory aerodynamic shape optimization. A definition is given for multidimensional SBP finite-difference operators that extends the classical one-dimensional definition. In the second portion of the talk, exploratory aerodynamic shape optimization is applied to a regional-class blended-wing body (BWB) aircraft configuration.
• 07/09/2015 Application of Improved Truncation Error Estimation Techniques to Adjoint Based Error Estimation and Grid AdaptationJoseph M. Derlaga, NASA Langley Research CenterThis seminar will examine the application of new, single-grid, truncation error estimation procedures for numerical CFD solutions to solve the problem of adjoint error estimation for both quasi-1D and 2D Euler equations. A new CFD code incorporating a variety of best practices from computer science, developed to complete this work, as well as a new method of performing code verification using the method of manufactured solutions will be discussed.
• 06/16/2015 Application of an Unstructured Grid RANS Model to the Coastal OceanMatthew D. Rayson, Stanford UniversityDr. Rayson presents 2 applications of the unstructured grid RANS model SUNTANS, used to investigate flows in the coastal ocean and continental shelf region: i) estuarine circulation and ii) internal wave dynamics. He will also summarize the model and challenges with acquiring forcing and observation data needed to run and validate a real-world numerical flow model in the natural environment.
• 06/09/2015 An Unsteady Continuous Adjoint Approach for Aerodynamic DesignThomas D. Economon, Stanford UniversityThe first portion of this talk presents the development and application of a new unsteady continuous adjoint formulation for optimal shape design of aerodynamic surfaces in motion, such as rotating or pitching applications. By leveraging shape calculus, the resulting surface formulation efficiently provides the gradient information necessary for performing gradient-based aerodynamic shape optimization. The second part of the presentation will highlight several open issues and future directions for adjoint-based methods related to robustness, accuracy, and performance.
• 06/05/2015 Exploiting Convex Structure in Aircraft Design OptimizationWarren Hoburg, Massachusetts Institute of TechnologyThe presentation will discuss primal-dual interior point methods developed and refined over the past two decades, which can be used to solve convex optimization problems such as geometric program (GP) that can be leveraged to reliably and efficiently explore conceptual aircraft design spaces. This approach provides a rich formalism for casting engineering design problems, including guarantees of global optimality, sensitivity analysis via Lagrange duality, and fitting of GP-compatible surrogate models to data. Limitations and extensions to non-convex design spaces will also be discussed.
• 05/26/2015 Eulerian Modeling and Simulation of Moderately Dense Spray Flows: Application to Solid Rocket MotorsFrançois Doisneau, Sandia National LabsThe presentation will discuss the challenges in accurately solving and modeling dense sprays, in which droplets may collide and coalesce or break-up, bringing a wide variety of sizes and dynamics (polydispersity). Eulerian models can describe the disperse phase at a moderate cost, with an easy coupling to the carrier phase and with massively parallel codes. This talk will also present some aspects of the modeling and numerical strategy to perform industrial computations of moderately dense spray flows.
• 05/21/2015 The NASA Aeronautics Advanced Air Transport Technology ProjectRubén Del Rosario, NASA Glenn Research CenterThe presentation will describe the current research and technology portfolio of the NASA Aeronautics Advanced Air Transport Technology (AATT) Project that addresses the project's objectives of delivering revolutionary improvements in energy efficiency combined with dramatic reductions in harmful emissions and perceived noise of future commercial transport aircraft. The project’s primary focus is on “N+3” generation aircraft that are three generations beyond the current state of the art, N, and require mature technology solutions in the 2025-30 timeframe.
• 05/05/2015 Radio Frequency Emission from Hypervelocity Impact PlasmaAlex Fletcher, Stanford UniversityThis seminar will present multi-physics simulations of meteoroid impact plasmas, which use a combination of computational continuum dynamics and discontinuous Galerkin particle-in-cell (PIC) techniques running on graphical processing units (GPUs). The results predict a minimum velocity threshold of ~18 km/s for fully ionized plasma production, which can produce electromagnetic pulse (EMP) that may threaten spacecraft electronics. Understanding key parameters of impact plasmas, as well as any EMP mechanisms, will aid in designing more robust and reliable spacecraft.
• 04/28/2015 NASA and the Future of FortranThomas Clune, NASA Goddard Space Flight CenterThis presentation will discuss the Fortran programming language, which continues to serve a mission-critical role in many NASA projects. The talk will begin with a high-level description of the committees and processes that govern the evolution of the Fortran language standard, and will then discuss some of the powerful new features introduced in the Fortran 2003 and 2008 standards, as well as capabilities that should be expected in the upcoming Fortran 2015 standard. The presentation will conclude with a discussion of how NASA can, and should, maximize its influence on the standard committee to ensure features the agency needs are given appropriate priority.
• 04/21/2015 Overview of GPU Suitability and Progress of CFD Applications, and Introduction of OpenACC for Directives-Based GPU Acceleration Stan Posey and Jeff Larkin, NVIDIA CorporationThis two-part seminar will discuss the use of graphics processing units (GPUs) as massively-parallel co-processors to CPUs within high performance computing, in order to accelerate numerical operations common to CFD solvers. The first part of the talk will examine GPU parallelization strategies for various CFD methods, and will provide examples of current implementations for research CFD software, including FUN3D from NASA. The second part of the talk will focus on OpenACC, which is a collection of compiler directives to specify loops and regions of parallel code. A brief introduction to OpenACC will be provided, along with the basics on utilization and current features.
• 04/14/2015 Evaluation of Linear, Inviscid, Viscous, and Reduced-Order Modeling Aeroelastic Solutions of the AGARD 445.6 Wing Using Root Locus Analysis Walter A. Silva, NASA Langley Research CenterReduced-order modeling (ROM) methods are applied to the CFD-based aeroelastic analysis of the AGARD 445.6 wing in order to gain insight regarding well-known discrepancies between the aeroelastic analyses and the experimental results. The results presented include aeroelastic solutions using the inviscid CAP-TSD code and the FUN3D code (Euler and Navier-Stokes). Full CFD aeroelastic solutions and ROM aeroelastic solutions, computed at several Mach numbers, are presented in the form of root locus plots in order to better reveal the aeroelastic root migrations with increasing dynamic pressure.
• 04/07/2015 An Adaptive Embedded Boundary Method for the Compressible Navier-Stokes EquationsDaniel Graves, Lawrence Berkeley National LaboratoryThis talk will present a new algorithm to solve time-dependent compressible Navier-Stokes equations in the presence of complex geometry using an embedded boundary method. The method is strongly conservative and second order accurate in space and time. This algorithm will be used to highlight the algorithmic choices that embedded boundary methods involve. The talk will also present some of the rich set of tools for embedded boundary calculations that the Chombo numerical infrastructure provides.
• 03/31/2015 Visualization and Quantification of Rotor Tip Vortices in Helicopter FlowsDavid Kao, Computational Technologies Branch, NASA Ames Research CenterThis presentation will discuss an automated approach for extraction, visualization, and quantification of vortex core radii from the Navier-Stokes simulations of a UH-60A rotor in forward flight. scaled Q criterion to determine vortex regions is adopted, and then vortex core profiling in these regions to calculate vortex core radii is performed, with the vortex core radii displayed graphically in a plane using a new color map scheme. This method represents an efficient way of visualizing and quantifying rotorcraft vortical flow fields.
• 03/30/2015 Computing Some Critical Multiscale Phenomena in Fluids and CombustionAhmed F. Ghoniem, Massachusetts Institute of TechnologyThis presentation will review the critical multiscale phenomena in energy and propulsion computational fluid dynamics, such as turbulence, flame stabilization and structural transitions, combustion dynamics and instability, etc. Ongoing work done by the group to address related computational challenges, focusing on recent simulations of selected processes in flame stabilization in turbulent jets and premixed combustion using hybrid Lagrangian-Eulerian methods and adaptive meshes with immersed boundaries will also be discussed.
• 03/26/2015 High-Order Linear and Non-Linear Residual Distribution Schemes for the Simulation of Compressible Viscous FlowsDante De Santis, Stanford UniversityThis presentation will describe implicit high-order Residual Distribution schemes for the solution of compressible Navier Stokes and RANS equations. Residual Distribution (RD) schemes represent an interesting alternative to Discontinuous Galerkin (DG) schemes, since in RD schemes, the formulation remains local, as in DG, but the number of degrees of freedom grows less quickly. The accuracy of the numerical scheme will be investigated and the method will be used to perform the simulation of several 2D/3D problems.
• 03/17/2015 Entropy-Stabilized Discontinuous Galerkin Method for Gas-Dynamics SimulationsMatthias Ihme, Stanford UniversityThis presentation will give an overview of recent development of a high-order shock-capturing framework, combining three key components: entropy-bounding, shock detection, and artificial viscosity. This framework is developed in the context of a discontinuous Galerkin (DG) method, and a local entropy constraint is introduced to guarantee numerical robustness. The second part of this talk will address the application of this entropy-bounded DG-framework to different flow configurations. Examples include hypersonic flows, shock-wave problems, unsteady wall bounded flows, turbulent flow simulations, and detonation transition.
• 03/12/2015 Strategies for Modularization and Integration of OVERFLOW and FUN3D into CREATE-AV Helios and its ApplicationsRohit Jain, US Army Aeroflightdynamics Directorate (AFDD), NASA Ames Research CenterThe presentation will discuss the strategies adopted in effort to integrate the Army's CREATE-AV Helios software with NASA's OVERFLOW CFD solver, including the handling of overset grid communications, and will show results from a few validation studies including the interactional aerodynamics of the HART-II rotor and hover predictions from the SciTech 2015 S-76 hover prediction workshop. On-going efforts on modularization of the NASA's FUN3D CFD solver as a Helios near-body unstructured grid solver will also be presented.
• 03/03/2015 Application of 3D Strand Mesh Technology to Rotorcraft HoverAndrew Wissink, US Army Aviation Development Directorate, NASA Ames Research CenterThis talk will discuss recent developments in an automated volume mesh generation capability based on "strands" and its application to hover calculations. This new approach is being developed as a means to to enhance automation in Helios, the Army's high-fidelity CFD/CSD rotorcraft simulation code. The volume mesh is composed of strand grids in the near-body to resolve the viscous boundary layer and Cartesian grids in the off-body to resolve the wake. Single and multi-strand per surface vertex strand meshes are evaluated.
• 02/24/2015 An Unexpected Journey in Rotorcraft CFDNeal Chaderjian, NASA Ames Research CenterThis talk will highlight the numerical and physical mechanisms involved in the accurate prediction of the hover and forward-flight performance of rotorcraft and the flow fields of the complex vortical wakes using time-dependent Navier-Stokes equations. Rotorcraft simulations are inherently unsteady and multidisciplinary, combining CFD, CSD, and a flight trim algorithm that determines the blade motions. Examples will draw upon results presented over the past four years and discussed in greater depth, drawing upon lessons learned from hundreds of CFD simulations.
• 02/17/2015 Optimized Off-Design Performance of Flexible Wings with Continuous Trailing-Edge FlapsDavid Rodriguez, NASA Ames Research CenterThis talk will present work which assesses the potential aerodynamic performance benefits of a variable-camber, continuous-trailing-edge flap system on a generic transport aircraft at off-design conditions, and a process to optimize transport wings while addressing static aeroelastic effects will be presented. To evaluate the effects of aeroelasticity on the effectiveness of the flap system, a transport wing is optimized at mid-cruise flight and off-design conditions for both a conventionally stiff wing and a modern, more flexible wing.
• 02/10/2015 Computational Challenges of the Aerodynamic Design Process in FORMULA 1Neil Ashton, University of ManchesterThis talk will focus on the Formula 1 design process, from conceptual design in CFD to wind tunnel testing and on-track testing. The aerodynamic design process needs to be both highly automated and efficient as new designs are required on a weekly basis for 20 races. This rapid turnaround time presents unique challenges for experimental testing and Computational Fluid Dynamics (CFD). Examples of the performance of various RANS models from the 1-equation Spalart-Allmaras model to advanced Reynolds Stress models will be demonstrated and discussed for simple cases as well as a complete Formula 1 car.
• 02/05/2015 Computational Aeroacoustic Analysis of a Jet Impinging on an Inclined PlateChristoph Brehm, NASA Ames Research CenterThis seminar covers a study of noise generation mechanisms for a supersonic Mach 18 turbulent jet impinging on an inclined plate. Methods used include large-eddy simulations, far-field acoustic propagation, and acoustic post-processing within the Launch Ascent and Vehicle Aerodynamics (LAVA) framework. Results showed excellent comparisons with experimental acoustic far-field measurements and pressure measurements on the impingement plane.
• 02/04/2015 Enchanting WavesGopalan Jagadeesh, Indian Institute of ScienceIn this seminar, Prof. Jagadeesh will give a broad overview of the research and technology development activities in Laboratory for Hypersonic and Shockwave Research (LHSR) in Indian Institute of Science. The presentation covers several LHSR-developed methods/facilities to generate high-speed shock waves, including novel techniques such as retractable aero-spikes, smart coatings, forward facing jets and concentrated energy deposition for reducing the aerodynamic drag around vehicles flying at hypersonic speeds.
• 01/27/2015 Parallel Adaptive High-Order CFD Simulations Characterizing SOFIA Cavity AcousticsMichael Barad, NASA Ames Research CenterThis seminar will talk about a one-of-a-kind MPI-parallel computational fluid dynamics simulation for the Stratospheric Observatory for Infrared Astronomy (SOFIA). Higher-order accurate simulations using NASA’s Launch Ascent and Vehicle Aerodynamics (LAVA) CFD solver will be presented. These simulations focus on how the unsteady flow field inside and over the cavity interferes with the optical path and mounting of the telescope. Limits to scaling beyond 32,000 cores on NASA's Pleiades supercomputer are identified, and targeted code optimizations are discussed.
• 01/20/2015 Adjoint-Based Error Estimation and Mesh Adaptation for Problems with Output ConstraintsMarco Ceze, NASA Ames Research CenterThis talk will discuss extending adjoint-based output error estimation and mesh adaptation to computational fluid dynamics simulations that involve trim constraints. For the reduction of numerical error in drag under fixed-lift conditions, the lift output comes only through the constraint, but numerical errors in the lift will indirectly affect the drag calculation. We present a method for including this effect in the output error calculation, and for adapting the discretization to better predict both the target output and the trim constraint.
• 01/16/2015 In Situ Post-Processing with VisIt, Libsim, and FieldViewBrad Whitlock, Intelligent LightDue to the widening gap between compute performance and the ability to store computation results, there is a growing need for simulation runs to include in situ data analysis and visualization. This seminar will discuss the need for in situ processing and provide steps for instrumenting simulations using Libsim, a library that enables the powerful Vislt visualization tool to request data as needed from a simulation and apply visualization algorithms in situ, with minimal code modifications. Instrumenting code using Libsim opens up new possibilities for higher productivity workflows, such as automatic creation of FieldView extract databases.
• 12/9/2014 Critical Trade-offs When Using Explicit DynamicsBence Gerber, Ansys, Inc.This seminar will discuss important considerations that influence how an accurate solution in explicit dynamics programs can be reached in the shortest possible time, including the quality of meshing, the type of solver (Lagrange/Euler/Meshfree) best suited for a specific problem, and the material models used. Trade-offs must be made between accuracy, computational time used and the effort needed to set-up a problem. Space related simulations, such as debris impact on a bumper shield and water landing of a space capsule will be used to illustrate how best to make those trade-off choices.
• 12/4/2014 CAE-based Robust Design OptimizationJohannes Will, DYNARDO GmbH, Weimar, GermanyThe seminar will cover methodology and software solutions addressing CAE-based Robust Design Optimization in virtual product development including large dimensions of optimization parameters, large dimensions of scattering variables and uncertainties, non-linear CAE-processes having non-linear and noisy design responses. The challenges, no goes and must’s will be discussed at industrial applications and the whole workflow will be illustrated at seal component of an hydraulic system.
• 12/2/2014 Adjoint-Based Topology and Shape Optimization for Car DevelopmentCarsten Othmer, Volkswagen AG, Corporate Research, Wolfsburg, GermanyThe adjoint method has long been considered as the tool of choice for gradient-based optimization in computational fluid dynamics and it is particularly attractive for problems with large design spaces. While it is now a standard tool in the development process of aeronautics, it is not as commonly used in the automotive industry. To drive adjoint-based shape optimization to the same degree of maturity and robustness for car applications is the subject of ongoing research collaborations between academia and the car industry. Achievements and challenges encountered during these efforts are presented.
• 11/26/2014 An Evaluation of Popular Noise Reduction Techniques for Multi-scale Problems Involving Particle Flow SimulationsMalgorzata Zimon, University of Strathclyde, United KingdomProper orthogonal decomposition (POD), widely utilized for turbulent flows, has recently been explored for processing particle data. An extension of the method based on time-windows offers a useful approach for noise reduction in particle simulations. In order to achieve better efficiency of POD in processing non-stationary fields, it has been combined with wavelet-based filtering. In this new procedure, the wavelet thresholding is performed within the POD's domain. Simulations were undertaken to illustrate the performance of the new tools applied to noisy velocity and density fields. Numerical examples include molecular dynamics, dissipative particle dynamics simulations, and direct Monte Carlo simulation of force-driven fluid flows and phase separation phenomena.
• 11/25/2014 An h/p Adaptive Discontinuous Galerkin Method for Shock Dominated High Speed FlowsJohn Ekaterinaris, Embry-Riddle Aeronautical UniversityThis presentation will discuss high order discontinuous Galerkin (DG) discretizations, which have features making them attractive for computations of 3D complex flows with shocks. A key element, which could make the DG method more suitable for these computations, is the application of limiting procedures that ensure accurate and crisp capturing of discontinuities for 3D complex flows in domains with nontrivial geometry. This unified limiting procedure for DG discretizations in unstructured meshes is well suited for h –, p –, and h/p dynamic adaptive refinement of the computed numerical solutions.
• 11/04/2014 A Failure Propagation Modeling Method for Launch Vehicle Safety AssessmentScott Lawrence, Systems Analysis Group, NASA Ames Research CenterThis presentation will discuss a method that has been developed with the objective of making the potentially intractable problem of launch vehicle failure propagation somewhat less intractable. The approach taken is to essentially decouple the potentially multi-stepped propagation process into a series of bi-component transition probabilities, which are then used within a simple Monte Carlo simulation process through which the more complex behavior emerges.
• 10/30/2014 Computational Studies for Sonic Boom PredictionJeff Housman, NASA Ames Research CenterComputational simulations using the Launch Ascent and Vehicle Aerodynamics (LAVA) framework are presented for the First AIAA Sonic Boom Prediction Workshop problems and an oblique shock/plume interaction test case. The framework is utilized with both structured overset and unstructured meshing approaches. The three workshop test cases include an axisymmetric body, a Delta Wing-Body model, and a complete low-boom supersonic transport concept.
• 10/23/2014 Overview Over Some Uncertainty Quantification (UQ) Activities in HypersonicsPietro Marco Congedo, INRIA Bordeaux Sud-OuestThis talk is focused on some activities about the application of uncertainty quantification techniques to hypersonic flows in the context of a long-term collaboration between INRIA and the von Karman Institute (VKI). The first study is oriented towards the characterization of physical and model uncertainties in two VKI facilities: the characterization of the free stream conditions in the VKI Longshot facility and the Uncertainty Analysis of Carbon Ablation in the VKI Plasmatron. Secondly, a sensitivity study over the interactions between the chemical reactions and their influence on the error of the radiative heat flux is presented.
• 10/16/2014 Automotive Design Space Exploration and OptimizationAndrea Shestopalov, EXA CorporationIn the automotive industry, aerodynamic optimization has to play a fine line between efficiency and inspiration, combining the emotion of the vehicle's design with the most efficient shapes. EXA accomplishes this goal by thinking beyond the analysis, using an analytical system using accurate simulations, allowing designers to focus on identifying styling features that influence the flow, and leaves the system to quantify effects to find the best combinations.
• 10/14/2014 Asteroid Threat ModelingDarrel Robertson, NASA Ames Research CenterThis presentation will focus on state-of-the-art modeling of asteroid entry and break-up in the atmosphere. Currently there is a very wide range of estimated damage that a given asteroid will do. We will aim to use physics based simulations of the break-up and blast to reduce the uncertainty in the modeling so that physical variables such as asteroid size, speed, composition, and strength are the dominant drivers of variation in predicted damage not the assumptions in the theory used.
• 10/07/2014 Cabin Environment Physics Risk ModelsChris Mattenberger, NASA Ames Research CenterThe Cabin Environment Physics Risk (CEPR) model estimates the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality on a crewed spacecraft to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. Discussed is an example where available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.
• 09/30/2014 Physics-Based Fragment Acceleration Modeling for Pressurized Tank Burst Risk AssessmentsTed Manning, NASA Ames Research CenterThis presentation will discuss coupled computational fluid and rigid body dynamic simulations which were carried out to investigate the flow mechanisms that accelerate tank fragments in bursting pressurized vessels. The improved tank burst model can be used to produce more accurate risk assessments of space vehicle failures involving high-speed debris.
• 09/25/2014 An Introduction to the Transformational Tools and Technologies (T3) ProjectJames D. Heidmann, NASA Glenn Research CenterThis presentation will give an overview of the Transformational Tools & Technologies (T3) Project, which was established by the NASA Aeronautics Research Mission Directorate. The project is investing in two main areas of research: Revolutionary Tools & Methods (RTM) to advance the state-of-the-art in physics-based simulation-based engineering, and Critical Aeronautics Technologies (CAT) to invent and develop the next generation of foundational concepts and technologies toward advancing NASA's Aeronautics mission.
• 09/23/2014 Pressure-based Coupled Simulation of Pressure Recovery and Distortion in an S-shaped Intake DiffuserKonstantine A. Kourbatski, Ansys, Inc.This presentation will look at the problem of a compressible flow through an S-shaped compact offset intake diffuser studied computationally using the general purpose CFD code Ansys Fluent. Steady-state converged solutions are calculated using second-order upwind discretizations. An effect of vortex generator vanes on pressure recovery and distortion is also studied.
• 09/18/2014 A Higher-Order Immersed Boundary Method for Solving the Compressible Navier-Stokes EquationsChristoph Brehm, NASA Ames Research CenterA higher-order immersed boundary method for solving the compressible Navier-Stokes equations will be presented. The distinguishing feature of this new immersed boundary method is that the coefficients of the irregular finite difference stencils in the vicinity of the immersed boundary are locally stabilized by solving a local optimization problem.
• 09/09/2014 Numerical Investigation of High Speed Boundary Layer Stabilization Through Porous WallsChristoph Hader, PhD Candidate, University of ArizonaLaminar to turbulent transition in high-speed flows can proceed along several paths and is still not completely understood. Previous studies have shown the potential of ultrasonically absorptive coatings (UACs) as a passive laminar flow control technique. In this work, the influence of porous walls on the linear and nonlinear stability regime of a Mach 6 Boundary Layer is investigated using temporal direct numerical simulations.
• 09/02/2014 OpenMP – Moving Beyond Shared-Memory ParallelismHenry Jin, NASA Ames Research CenterThis talk will present the recent development in OpenMP 4.0 for supporting accelerated devices and vector parallelism. We will also discuss some of the challenges in achieving desired performance as well as future effort in the language standard. OpenMP has been the de-facto standard for shared-memory parallel programming since its first release in 1997.
• 08/28/2014 High-Order CFD and Multi-Scale Modelling for Aerospace and Nanotechnology ApplicationsDimitris Drikakis, Institute of Aerospace Sciences, Cranfield UniversityAdvances in computational methods have increasingly enabled the simulation of complex engineering problems, but reducing the uncertainty by increasing the accuracy, while making computations more efficient still remains a scientific challenge. This presentation will show results from our recent research with respect to the development and application of high-order CFD and multi-scale/multi-physics methods for aerospace and nanotechnology applications.
• 08/27/2014 Coupled Nonlinear Aeroelasticity and Flight Dynamics of Highly Flexible AircraftWeihua Su, University of AlabamaA methodology that can effectively model and analyze nonlinear aeroelasticity of the very flexible High-Altitude, Long-Endurance (HALE) aircraft will be addressed in this talk. The new framework integrates a strain-based geometrically nonlinear beam model, a finite-state unsteady subsonic aerodynamic model, and a 6-DoF rigid-body flight dynamic formulation, which allows for the coupled nonlinear aeroelastic and flight dynamic analysis of highly very flexible aircraft in free flight.
• 08/26/2014 Measuring and Modeling the Transport of Magnetic Flux at the Surface of the Sun – Toward Solving One-Half of the Solar Dynamo ProblemDavid Hathaway, NASA Ames Research CenterThis talk will discuss models for the transport of magnetic flux at the Sun's surface, which are key to understanding the solar dynamo that produces the sunspot cycle. Previous models of magnetic flux transport parameterized the non-axisymmetric components as a diffusive process and often used meridional flow profiles that were poorly constrained by observations. Efforts to fully characterize all flows involved and to model the magnetic flux transport using these flows will also be described.
• 08/19/2014 A Comparison of Higher-Order Finite-Difference Shock Capturing SchemesChristoph Brehm, NASA Ames Research CenterThis presentation assesses shock capturing capabilities as well as effects on the accuracy in smooth flow regions for unsteady turbulent flow CFD simulations involving shocks, contacts, and/or material discontinuities. A new set of boundary candidate stencils for an upwind-biased compact weighted essentially non-oscillatory scheme are proposed which offer improved accuracy and stability at block and/or domain boundaries.
• 08/12/2014 An Explicit 3D Cartesian Discontinuous Galerkin Spectral Element Compressible Navier-Stokes SolverAndrew Kirby, University of WyomingThis seminar will discuss a parallel Cartesian Discontinuous Galerkin Spectral Element solver developed to solve Compressible Navier-Stokes equations. Results include test comparisons from the International Workshop on High-Order CFD Methods and timing comparisons with finite difference methods. Parallel scalability is demonstrated up to 16,384 processor cores.
• 08/06/2014 Adaptive Aeroelastic Wing Shape Optimization for High-Lift ConfigurationsGustavo Fujiwara, PhD candidate, University of WashingtonThis work presents the development of a 3D aerodynamic analysis tool to be used in an aeroelastic framework for multidisciplinary optimization of a flexible wing with variable camber continuous trailing-edge flaps (VCCTEF) in high-lift configurations, such as those encountered during takeoff and landing. A hybrid 3D aerodynamic formulation was developed by combining linear vortex lattice method with nonlinear lifting-line theory, utilizing 2D viscous sectional aerodynamic data.
• 08/05/2014 Adaptive Time-Space Algorithms for the Simulations of Multi-Scale Reaction WavesMarc Massot, Fédération de Mathématiques de l’Ecole Centrale ParisThis seminar will introduce a new resolution strategy for multi-scale reaction waves based mainly on time operator splitting and space adaptive multiresolution. It considers high order time integration methods for reaction, diffusion and convection problems, in order to build a time operator splitting scheme that exploits efficiently the special features of each problem. Applications will be presented in the fields of combustion waves and plasma discharges dynamics as well.
• 07/31/2014 From Microtomography to Modeling of the Fiber-Scale Oxidation of Highly-Porous Carbon MaterialsJoseph Ferguson, University of KentuckyThis seminar will discuss models used to simulate the microscale process of oxidation on thermal protection materials NASA uses for lightweight planetary entry systems. To enable high fidelity simulations of the decomposition of the fibers, digitized computational grids are obtained from X-ray microtomography of the Fiberform, the substrate used in PICA.
• 07/29/2014 To Infinity and Beyond: Diatomic Molecules Above the Dissociation LimitDavid W. Schwenke, NASA Ames Research CenterThis seminar will discuss progress made in predicting the behavior of diatomic molecules above the dissociation limit. The most intense radiators in Earth re-entry are highly excited nitrogen atoms, with emission in the vacuum ultra violet (VUV), which have enough energy to dissociate even the most strongly bound molecules. The spectroscopic data required for the radiative transfer calculations for this situation is incomplete and we have been carrying out first principle calculations of these properties to fill the gaps, which has necessitated the development of new techniques for treating these very complex situations.
• 07/24/2014 Design in Chaos—the Least Squares Shadowing technique for Sensitivity Analysis of Chaotic High Fidelity SimulationsQiqi Wang, Massachusetts Institute of TechnologyThis talk introduces the Least Squares Shadowing technique to overcome the challenge of sensitivity analysis in chaotic simulations. The shadowing condition replaces the initial condition, and enforces that similar design variables develop similar trajectories that "shadow" each other. The theory, computation and potential applications of the Least Squares Shadowing technique will be discussed.
• 07/17/2014 COOLFluiD: An Open Computational Platform for Plasma and Multi-physicsAndrea Lani, the Von Karman Institute for Fluid DynamicsCOOLFluiD features a modern object-oriented infrastructure, a unique collection of parallel numerical solvers for unstructured meshes, where each physical model or numerical algorithm is enclosed in a separate component which is loaded dynamically at run-time. The seminar will present some of the main strengths and scientific results of the platform in terms of reusable code design, advanced computational models and an overview of research applications. Particular attention will be devoted to aspects in the modelling of aerothermodynamics and all-speed plasma flows, including atmospheric re-entry flows in thermo-chemical nonequilibrium, fluid-radiation coupling, experiments in high-enthalpy facilities, space weather, fluid-elecromagnetics coupling.
• 07/16/2014 HPC Applications with Adaptive Runtime SystemsLaxmikant Kale, University of IllinoisAdaptive runtime systems (ARTSs) are expected to be a major tool for efficiently exploiting complex extreme scale machines of near future for sophisticated science and engineering applications. This talk will examine what capabilities such ARTS offer, and what application writers can start doing today to get ready for leveraging this powerful tool. It will also discuss why it is essential to re-factor the application software in such a way that certain performance related responsibilities, such as resource management, are handed over to the runtime system.
• 07/10/2014 Advances in SBP-SAT-Based Methods for the Prediction and Control of Compressible Turbulent FlowsDaniel J. Bodony, University of IllinoisThis presentation will discuss new developments towards provably stable numerical schemes, without artificial dissipation, appropriate for the prediction and control of compressible turbulent flows in the presence of complex geometries. We leverage the summation-by-parts / simultaneous-approximation-term (SBP-SAT) framework.
• 07/01/2014 How Wrong Can a Flow Model Be, and Yet Provide Reasonable Acoustic Predictions?Christophe Schram, von Karman Institute for Fluid DynamicsThis talk will review some of the fundamental assumptions that are involved in two important aeroacoustic analogies, Curle's analogy and Vortex Sound Theory, and will illustrate the numerical robustness issues that arise when an inadequate interpretation of the flow data is made. In contrast, it will be shown that aeroacoustical analogies allow using relatively crude flow models through a careful filtering of the non-physical spurious sources of sound.
• 06/26/2014 Advances in Boundary Layer Investigations and Heat Flux Measurements in 1.2 MW VKI PlasmatronDaniel Guariglia, von Karman Institute for Fluid DynamicsThis talk will introduce experimental measurement techniques that have been implemented at the von Karman Institute's Plasmatron facility, in order to investigate the boundary layer developing in cold wall conditions at low and high heat flux, and att low and high total pressure.
• 06/26/2014 Gas/Surface Interaction Study of Low-Density Ablators in Sub- and Supersonic PlasmasBernd Helber, von Karman Institute for Fluid DynamicsThis talk will discuss ablation experiments which were carried out with the carbon-phenolic material AQ61 and a non-pyrolizing carbon fiber preform in sub- and supersonic air and nitrogen plasmas at the von Karman Institute's Plasmatron facility.
• 06/26/2014 Development of Mutation++: Multicomponent Thermodynamic and Transport Properties for Ionized Plasmas written in C++J.B. Scoggins, von Karman Institute for Fluid DynamicsThis talk will describe the development of the Mutation++ library, which has been designed to compute thermodynamic and transport properties of ionized gases, including equilibrium compositions and species production rates due to finite-rate elementary reactions.
• 06/24/2014 Understanding and Optimizing the Performance of Scientific SoftwareBoyana Narris, University of OregonThis talk will present approaches and tools that reduce the need for involving multiple experts during the development and performance optimization of scientific software, and will describe two main areas where these approaches might be utilized: performance modeling using an approach implemented in the PBound tool and semi-automated tuning of numerical computations using the Orio auto tuning framework.
• 06/10/2014 Computational Framework for Launch, Ascent, and Vehicle Aerodynamics (LAVA)Cetin C. Kiris, NAS Applied Modeling & Simulation Branch, NASA Ames Research CenterThis talk will present the Launch, Ascent, and Vehicle Aerodynamics (LAVA) framework developed at NASA Ames Research Center, a grid-flexible computational fluid dynamics solver that also features auxiliary modules for conjugate heat transfer and computational aero-acoustics capabilities. Two validation studies from NASA's Fundamental Aeronautics program will be presented, as well as highlights from selected test cases.
• 06/03/2014 Calculation of State-Specific Rate Coefficients for Non-equilibrium Hypersonics ApplicationsRichard L. Jaffe, Entry Systems Technology Division, NASA Ames Research CenterThis presentation will discuss accurate theoretical methods used to compute ro-vibrational state-specific rate coefficients needed to model the high-temperature chemistry for N₂-O₂ and CO₂-N₂ mixtures to describe Earth and Mars entry, respectively, to study the chemical changes to gases during atmospheric entry at hypersonic speeds. In order to accurately model this process, scientists must know rate coefficients or cross sections for the relevant collisional dissociation, exchange reactions and ro-vibrational relaxation. The presentation will focus on dissociation and relaxation processes encountered during Earth entry at 8-12 km/s.
• 05/29/2014 The OVERGRID Graphical User Interface in Chimera Grid Tools (Part 3)William M. Chan, NAS Applied Modeling & Simulation Branch, NASA Ames Research CenterThe final presentation/demonstration of this three-part series will focus on visualization of flow solutions for steady, unsteady, moving-body, and adaptive grid simulations; viewing local contributions to vehicle forces and moments, and animation of component dynamics from coupled 6-DOF computations. Part 1 covered an introduction to OVERGRID and demonstrated key functions for geometry, grid visualization, grid editing, redistribution, and surface curves. Part 2 continued the demonstration of grid-generation modules, grid diagnostics, flow solver input preparation, and more.
• 05/20/2014 The OVERGRID Graphical User Interface in Chimera Grid Tools (Part 2)William M. Chan, NAS Applied Modeling & Simulation Branch, NASA Ames Research CenterThis is the second of a two-part presentation. In Part 1, a short overview talk covered an introduction to OVERGRID, and was followed by a demonstration of the main functions for geometry and grid visualization, grid editing, redistribution, and surface curves creation. In Part 2, the software demonstration will continue and will focus on the modules for grid generation, overset grid diagnostics, flow solver input preparation, solution visualization, and prescribed and 6-DOF component dynamics.
• 05/13/2014 The OVERGRID Graphical User Interface in Chimera Grid Tools (Part 1)William M. Chan, NAS Applied Modeling & Simulation Branch, NASA Ames Research CenterThis presentation will be split into two parts. In Part 1, a short overview talk will cover an introduction to OVERGRID. This will be followed by a demonstration of the main functions for geometry and grid visualization, grid editing, redistribution, and surface curves creation. Part 2 of the talk will discuss the software demonstration will continue and will focus on the modules for grid generation, overset grid diagnostics, flow solver input preparation, solution visualization, and prescribed and 6-DOF component dynamics.
• 04/29/2014 Compressibility Effects on Boundary Layer Receptivity and Dielectric Barrier Discharge Plasma ActuationMarie Denison, Texas InstrumentsThis talk will present a detailed understanding of receptivity in compressible flows that is essential to devise efficient boundary layer stability control strategies for high-speed aerodynamics and inlets. To date, little work as been devoted to the analysis of how flow regime and geometry dependent receptivity information can be used to maximize flow control authority. The present work takes steps in this direction, through a two-dimensional analysis of the receptivity of supersonic flows over a flat plate.
• 04/22/2014 A Framework for Adaptive Aeroelastic Wing Shaping ControlNhan Nguyen, NASA Ames Research CenterThis talk will present the current research element Adaptive Aeroelastic Shape Control being conducted under the NASA Fixed Wing project for the Aerodynamic Efficiency sub-project. Modeling approaches for aeroelasticity, flutter analysis, and aeroelastic coupling with rigid-body 6-dof aircraft flight dynamics will be discussed. An actuation concept called Variable Camber Continuous Trailing Edge Flap (VCCTEF) will be presented as an embodiment of the adaptive aeroelastic wing shaping control framework.
• 04/15/2014 Launch Environment Water Flow Simulation Using Smoothed Particle HydrodynamicsBruce Vu, NASA Kennedy Space CenterIn this seminar, Dr. Vu will discusses the use of Smoothed Particle Hydrodynamics (SPH) to simulate water flow of the "rainbird" nozzle system, which is used to suppress acoustic energy generated by launch vehicles at Kennedy Space Center. SPH, a mesh-free method of simulating fluid flows that utilizes nodal collocation, spatial discretization, and kernel approximation, is computationally intensive. However, recent advances in Graphical Processing Unit (GPU) technology that overcome this disadvantage will be discussed.
• 04/08/2014 Aeroacoustics of Space VehiclesJayanta Panda, Experimental Flow-Physics Branch, NASA Ames Research CenterThis presentation will cover all three major sources of aeroacoustics associated with community noise encountered in manned and unmanned space vehicles: launch acoustics, ascent acoustics and abort acoustics. Examples of wind tunnel tests and computational simulations to optimize the outer mold line to quantify and reduce the surface pressure fluctuations which cause vibrations and noise will be presented.
• 04/03/2014 Preliminary Assessment of the Boundary Layer Ingestion Benefit for the D8 AircraftShishir Pandya, NAS Applied Modeling & Simulation Branch, NASA Ames Research CenterThis talk will present the results of computational and wind tunnel tests conducted for the D8 next-generation subsonic transport concept in the Boeing 737 class, which uses various means to improve fuel efficiency and lower environmental impact. The computational approach consists of solutions on overset surface and volume grids using OVERFLOW, a viscous overset RANS CFD solver with an actuator-disk propulsor model.
• 03/25/2014 An Embedded Hybrid RANS-LES Approach for 3D Separated FlowsNeil Ashton, University of ManchesterThis talk will discuss the use of hybrid RANS-LES methods for 3D separated flows using code_saturne, an open source finite-volume code (developed by EDF energy and the University of Manchester) as well as the commercial code Star-CCM+. The use of a one-way embedded approach for several flows including the Ahmed car body (a flow subject to 3D separation and reattachment induced by two counter-rotating vortices) and the future use of the approaches for more complex geometries is also explored.
• 03/18/2014 Multifidelity Airfoil Optimization with Adjoints and Mesh AdaptationDerek Dalle, Raytheon Missile SystemsThis talk will focus on gradient-based aerodynamic shape optimization using adaptive mesh refinement on each design iteration, which can reduce optimization time. The approach is tested on two airfoil optimization test cases, and it is compared in computational expense to other approaches, which include a traditional fixed-mesh optimization, optimization using a constant level of fidelity, and multifidelity optimization using uniform refinement.
• 03/13/2014 An Overset Time-Spectral Method for Relative MotionJoshua Leffell, Stanford UniversityThis talk will present a hybrid Time-Spectral scheme that extends the temporal variation at dynamically-blanked nodes in an alternative manner implemented within NASA's implicit Reynolds-averaged Navier-Stokes solver OVERFLOW and demonstrated on the two- and three-dimensional cases of oscillating airfoils and the quarter-scale V22 Tilt Rotor Aeroelastic Model (TRAM) in hover and forward flight.
• 03/04/2014 Best Practices for Hover Calculations using HeliosAndrew Wissink, NASA/AmesThis talk will discuss rotary-wing hover calculations using Helios, the US Army's next-generation high-fidelity CFD/CSD rotorcraft simulation code. Helios uses a hybrid dual-mesh paradigm consisting of unstructured meshes near the body to capture viscous flow and complex geometry coupled with block structured Cartesian grids away from the body that capture the wake through a combination of high-order algorithms and adaptive mesh refinement (AMR).
• 02/25/2014 Arrive Before Leaving, The Challenge of Supersonic Aircraft DesignFrancisco Palacios, Department of Aeronautics and Astronautics, Stanford UniversityThis talk will discuss rotary-wing hover calculations using Helios, the US Army's next-generation high-fidelity CFD/CSD rotorcraft simulation code, and will present an analysis of hover calculations with Helios examining the effect of different mesh resolutions, different reference frames, and DES turbulence modeling in the wake.
• 02/18/2014 Compressible Flow Solvers and Uncertainty Analysis on Million-Core ArchitecturesIvan Bermejo-Moreno, Center for Turbulence Research, Stanford UniversityScaling and performance studies will be presented for two compressible flow solvers developed at the Center for Turbulence Research: Hybrid, a structured-mesh, finite-difference code used for DNS and LES of shock/turbulence interaction; and CharLESx, an unstructured-mesh, finite-volume code used for LES in arbitrarily complex geometries, including combustion and wall models.
• 02/11/2014 Cart3D Simulations for the First AIAA Sonic Boom Prediction WorkshopMichael J. Aftosmis, Applied Modeling & Simulation Branch, NASA Ames Research CenterSimulation results for the First AIAA Sonic Boom Prediction Workshop are presented using an inviscid, embedded-boundary Cartesian mesh method. The method employs adjoint-based error estimation and adaptive meshing to automatically determine resolution requirements for each simulation. Results are presented for both mandatory and optional test cases.
• 02/04/2014 Computational and Experimental Assessment of Models for the First AIAA Sonic Boom Prediction WorkshopSusan Cliff, Applied Modeling & Simulation Branch, NASA Ames Research CenterNear-field sonic boom pressure signatures were measured and computational predictions made for a Lockheed-Martin Aeronautics Company low-boom supersonic transport concept, an axisymmetric calibration model, and a 69° swept delta wing-body configuration. The pressure signatures were measured in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel at Mach 1.6 and 1.7 in 2011 and 2012.
• 01/28/2014 Mechanism of Local Dynamo Action on the SunIrina Kitiashvili, Research Fellow, NASA Ames Research Center
• 01/21/2014 Static Aeroelastic Analysis with an Inviscid Cartesian MethodDavid L. Rodriguez, STC / Applied Modeling & Simulation Branch, NASA Ames Research Center
• 01/08/2014 The Next 40 Years of Supersonic Aerodynamic Decelerators: An Overview of the Low-Density Supersonic Decelerator ProjectIan G. Clark, NASA Jet Propulsion Laboratory
• 12/16/2013 Ablator Response ModelingNagi Mansour, NASA Advanced Supercomputing Division, NASA Ames Research Center
• 12/10/2013 Challenges and Opportunities in Combustion Research Description of AFOSR Energy Conversion and Combustion Sciences ProgramChiping Li, The Air Force Office of Scientific Research (AFOSR)
• 12/05/2013 Turbulence Induced Solid Surface Temperature FluctuationAnirban Garai, Postdoctoral Fellow, NASA Ames Research Center
• 11/25/2013 Survey on Projects at DLR Simulation and Software Technology with Focus on Software Engineering and HPCAndreas Schreiber and Achim Basermann, German Aerospace Center (DLR)
• 11/14/2013 Flow Induced Vibrations for Energy Harvesting: Experiments and a SimulationDogus Akaydin, Postdoctoral Fellow, Department of Mechanical Engineering, Stanford University
• 11/12/2013 Improving Entry Vehicle Shape Optimization via a Guidance Algorithm for Trajectory GenerationSarah D’Souza, Systems Analysis Project Office, NASA Ames Research Center
• 11/07/2013 Large Eddy Simulation with Unstructured High-Order Numerical Methods for Real-World Turbulent FlowsJonathan R. Bull, Postdoctoral Research Fellow, Stanford University
• 10/29/2013 Material Failure Modeling Due to Electromigration and Other ProcessesMetin Ozen, Ozen Engineering, Inc., Sunnyvale, CA
• 10/22/2013 Surely there must be a faster way of doing LES?...Paul Batten, Metacomp Technologies, Inc., Agoura Hills, CA
• 09/26/2013 Towards A Physical Understanding of Rocket Plume Impingement: A Jet Impingement Model ProblemChristoph Brehm, STC / Applied Modeling & Simulation Branch, NASA Ames Research Center
• 09/17/2013 Analysis of Low-Speed Stall Aerodynamics of a Swept Wing with Laminar-Flow GloveTrong T. Bui, Aerodynamics and Propulsion Branch, NASA Armstrong Flight Research Center
• 09/10/2013 Post-Processing Modules in Chimera Grid ToolsWilliam Chan and Shishir Pandya, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 09/05/2013 Platform Approach to Automatic Mesh Generation and Computational Engineering AnalysesKenji Shimada, Carnegie Mellon University
• 08/27/2013 Microgravity: past, present and futureIoana Cozmuta, Science and Technology Corporation, Space Portal / NASA Ames Research Center
• 08/15/2013 Summer Intern PresentationsJames Jensen, Arizona State University; Arseniy Kotov, CAL POLY San Louis-Obispo; and Sean Ballinger, Columbia University
• 08/06/2013 Modeling and Simulation of Fragment Dynamics in Launch Vehicle ExplosionsTed Manning, NASA Ames Research Center
• 07/23/2013 Comprehensive Study of the Flow Around a Simplified Orion Capsule ModelJames Ross, NASA Ames Research Center
• 07/18/2013 Unstructured Viscous Meshing Best Practices by ExampleTravis Carrigan, Pointwise Inc., Fort Worth, TX
• 07/16/2013 Visualization and Post-Processing of Large Scale Engineering ApplicationsSteve M. Legensky and Dr. Earl P.N. Duque, Intelligent Light
• 07/09/2013 A New Paradigm for LES of Complex Turbulent FlowsSanjeeb T. Bose, Cascade Technologies, Inc., Palo Alto CA
• 07/03/2013 Toward Accurate Simulation of Shockwave-Turbulence Interaction on Unstructured Meshes: A Coupling of High-Order FR and LAD SchemesTakanori Haga, Japan Aerospace Exploration Agency (JAXA)
• 07/02/2013 A Novel Application of Flame Hole Dynamics to Consistent Turbulent Nonpremixed Combustion ModelingCarlos Pantano, University of Illinois at Urbana-Champaign
• 06/20/2013 Dynamic Adaptive Sampling Based on Kriging Surrogate Models for Efficient Uncertainty QuantificationKoji Shimoyama, Tohoku University, Japan
• 06/11/2013 Second-Derivative Calculations using Hyper-Dual NumbersJeffrey A. Fike, Ph.D. Candidate, Department of Aeronautics and Astronautics, Stanford University
• 06/05/2013 Comparison of Computed and Measured Vortex Evolution of Helicopter Flowfield in Forward FlightJasim Ahmad, Applied Modeling and Simulation Branch, NASA Ames Research Center
• 05/28/2013 Synchrotron Hard X-ray MicrotomographyDula Parkinson, Lawrence Berkeley National Laboratory
• 05/21/2013 Toward Ablative Material Response Coupling in Aerothermal Applications of CFDMichael Barnhardt, ERC Inc. / Aerothermodynamics Branch, NASA Ames Research Center
• 05/13/2013 A Hybrid Adjoint Approach for Systems of Arbitrarily Complex Partial Differential EquationsThomas W. R. Taylor, Ph.D. candidate, Department of Aeronautics and Astronautics, Stanford University
• 04/30/2013 Realizing Discontinuous Galerkin Methods for AerodynamicsNicholas K. Burgess, STC / U.S. Army Aeroflightdynamics Directorate
• 04/23/2013 Compass: A Scalable Simulator for a Cognitive Computing Hardware ArchitectureTheodore M. Wong, IBM Research, Almaden, CA
• 04/16/2013 Investigation of Nonequilibrium Radiation for Mars EntryAaron M. Brandis, ERC Inc. / Aerothermodynamics Branch, NASA Ames Research Center
• 04/02/2013 Some Highlights of ONERA High-Speed Aerodynamics ResearchGérald Carrier, Applied Aerodynamics Department, ONERA, Meudon Center, France
• 03/26/2013 Simulation of Reentry Radiative Heating with HyperRadAlan Wray, Fundamental Modeling and Simulation Branch, NASA Ames Research Center
• 03/19/2013 Numerical Simulations of Solar and Stellar Turbulent DynamicsIrina Kitiashvili, Center for Turbulence Research, Stanford University
• 03/14/2013 Chimera Grid Tools An Overview and an Introduction to the Script LibraryWilliam Chan and Shishir Pandya, Applied Modeling and Simulation Branch, NASA Ames Research Center
• 03/05/2013 Integrated Nacelle-Wing Shape Optimization for an Ultra-High Bypass Fanjet Installation on a Single-Aisle Transport ConfigurationStephen C. Smith, NASA Ames Research Center
• 02/26/2013 Model-Based Design Optimization: a new paradigm in system engineeringSerdar Uckun, Founder and CEO, CyDesign Labs, Palo Alto, CA
• 02/21/2013 Symmetric-Conservative-Metric Evaluations for Higher-Order Finite DifferencesTaku Nonomura, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
• 02/12/2013 Adjoints for Embedded-Boundary Methods: From Analysis to DesignMarian Nemec, STC / Applied Modeling & Simulation Branch, NASA Ames Research Center
• 02/05/2013 A Scalable Adaptive Spatial Discretization for Incompressible Flow Using Overset Cartesian GridsElliot English, Ph.D. Candidate, Dept. of Computer Science, Stanford University
• 01/29/2013 Initial Assessment of Mars Science Laboratory Entry Instrumentation DataDeepak Bose, Aerothermodynamics Branch, NASA Ames Research Center
• 01/22/2013 Simulation of Meteoroid Impact Induced Electrical Anomalies on SpacecraftAlexander Fletcher, Ph.D. Candidate, Dept. of Aeronautics & Astronautics, Stanford University
• 12/04/2012 Progress and Challenges in Liquid Rocket Combustion Stability ModelingVenke Sankaran, AFRL/RQ, Edwards Air Force Base
• 11/27/2012 Viscous Hypersonic Flow Physics Predictions using Unstructured Cartesian Grid TechniquesNASA Postdoctoral Fellow, NAS Ames Research Center
• 11/08/2012 Solving Fluid Structure Interaction Problems on Overlapping GridsBill Henshaw, Lawrence Livermore National Laboratory
• 10/30/2012 DNS and Modeling of a Turbulent Boundary Layer with Separation and Reattachment over a Range of Reynolds NumberHiroyuki Abe, Japan Aerospace Exploration Agency (JAXA)
• 10/30/2012 Computational Fluid Dynamics, Past, Present and FutureAntony Jameson, Department of Aeronautics and Astronautics, Stanford University
• 10/23/2012 Analysis of Correlations for Natural Convection and Temperature Stratification in Cryogenic TanksMichael Khasin, Applied Physics Group, NASA Ames Research Center
• 10/18/2012 How to Compute with Schroedinger's Cat: Introduction to Quantum ComputingEleanor Rieffel, NASA Advanced Supercomputing Division, NASA Ames Research Center
• 10/16/2012 Accurate Measurement of Low Sonic Boom (or Model Surface Pressures) in Supersonic Wind TunnelsJohn Morgenstern, Lockheed Martin Aeronautics Company
• 10/09/2012 On Heatshield Shapes for Mars Entry CapsulesDinesh K. Prabhu, ERC Inc. / Entry Systems & Technology Division, NASA Ames Research Center
• 10/02/2012 Software Design Strategies for Multidisciplinary Computational Fluid DynamicsRoger Strawn, US Army Aeroflightdynamics Directorate, AMRDEC, Moffett Field, CA
• 09/26/2012 Helios Solver Developments Including Strand MeshesAndrew Wissink, US Army Aeroflightdynamics Directorate, AMRDEC, Moffett Field, CA
• 09/18/2012 Toward Hybrid Grid CFD Simulations of the Launch EnvironmentShayan Moini-Yekta, Ph.D. Candidate, University of California at Davis / NASA Ames Research Center
• 09/13/2012 High Fidelity Optimization of Flapping Airfoils and WingsMatthew Culbreth, Ph.D. Candidate, Dept. of Aeronautics & Astronautics, Stanford University
• 09/04/2012 Overheating Anomalies during Flight Test due to the Base BleedingDmitry G. Luchinsky, MCT Inc. / NASA Ames Research Center
• 08/30/2012 Summary of Data and Findings drom the First Aeroelastic Prediction WorkshopDavid Schuster, NASA Langley Research Center
• 07/24/2012 Integrated Structures/Aerodynamics/Controls Optimization of Flight VehiclesEli Livne, Department of Aeronautics and Astronautics, University of Washington
• 07/18/2012 Applications of the Adjoint in Unsteady CFD ProblemsKarthik Mani, University of Wyoming
• 07/16/2012 Exploiting Petascale Platforms for Reliable LES of Turbulent Combustion via the Filtered Density FunctionLevent Yilmaz, University of Pittsburgh
• 06/19/2012 A Historical Perspective of the NASA Ames CFD Branch: ARC2D to OVERFLOWThomas H. Pulliam, Fundamental Modeling & Simulation Branch, NASA Ames Research Center
• 06/12/2012 Advances in Domain Connectivity for Overset Grids Using the X-rays ApproachWilliam M. Chan, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 06/07/2012 External Aerodynamics Simulations on the D8 "Double-bubble" AircraftShishir Pandya, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 05/29/2012 Automatic Hole-cutting in Overset Grids using the X-rays ApproachNoah Kim, Ph.D. Candidate, Department of Mechanical Engineering, Stanford University
• 05/15/2012 Improvements to the Pegasus5 Overset CFD SoftwareStuart E. Rogers, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 05/01/2012 Capturing Shocked Flows with High-order DG MethodsDr. Nicholas Burgess, U.S. Army Aeroflightdynamics Directorate / STC, NASA Ames Research Center
• 04/24/2012 The 9x7 Wind Tunnel Sonic Boom Measurements and Computational-Experiment ComparisonsSusan Cliff, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 04/17/2012 Optimization and Adjoint-Based CFD for the Conceptual Design of Low Sonic Boom AircraftMathias Wintzer, Ph.D. candidate, Dept. of Aeronautics & Astronautics, Stanford University
• 04/10/2012 Finite Volume Robustness in Uncertainty QuantificationJeroen Witteveen, Postdoctoral Research Fellow, Center for Turbulence Research (CTR), Stanford University
• 04/03/2012 Continuing Challenges to Commercial CFD Software in Aeroacoustic SimulationFred Mendonca, CD-adapco
• 03/27/2012 Time-Accurate Anisotropic Mesh Adaptation Using Hessian-Based or Goal-Oriented Error EstimatesFrederic Alauzet, INRIA, France
• 03/20/2012 Evaluation of the High Lift Prediction Workshop Data Using Simulation AnalyticsDurrell Rittenberg, Tecplot Inc., Bellevue, WA
• 03/13/2012 High-Order Methods for the Reynolds Averaged Navier-Stokes EquationsNicholas Burgess, U.S. Army Aeroflightdynamics Directorate / STC, NASA Ames Research Center
• 03/06/2012 Advances in Design Methodologies for Low-Boom SupersonicsMichael R. Colonno, Dept. of Aeronautics & Astronautics, Stanford University
• 02/28/2012 How to Predict Near and Far Field Acoustics : A Unique Aeroacoustics Approach with Designs to Control Noise of Launch Vehicles and Transport AircraftNesrin Sarigul-Klijn, University of California, Davis
• 02/21/2012 Real-Time Flutter Predictions Using Databases of Reduced-Order MethodsDavid Amsallem, Dept. of Aeronautics & Astronautics, Stanford University
• 02/14/2012 A Novel Approach for the Design of Immersed Boundary/Interface MethodsChristoph Brehm, University of Arizona
• 02/10/2012 Reflections on RANS ModelingPhilippe R. Spalart, The Boeing Company
• 02/07/2012 Parametric Deformation of Discrete Geometry for Aerodynamic Shape DesignGeorge Anderson, Ph.D. candidate, Dept. of Aeronautics & Astronautics, Stanford University
• 01/31/2012 Large Eddy Simulation of Shock Induced Separated FlowsBrandon Morgan, Ph.D. candidate, Dept. of Aeronautics & Astronautics, Stanford University
• 01/24/2012 An Overview of Uncertainty Quantification Methods for Conservation Laws with DiscontinuitiesTimothy Barth, Fundamental Modeling & Simulation Branch, NASA Ames Research Center
• 01/17/2012 A High Order Accurate Discontinuous Galerkin (DG) Method For 3D Compressible Flows In Complex GeometriesJohn Ekaterinaris, University of Patras, Greece
• 12/13/2011 A Hybrid Implicit-Explicit Method for the LES of Compressible Flows on Unstructured GridsMohammad Shoeybi, Cascade Technologies Inc., Palo Alto, CA
• 12/06/2011 The Impact of Hyper-Threading on Processor Resource Utilization in Production ApplicationsSubhash Saini, Computational Technologies Branch, NASA Ames Research Center
• 11/29/2011 Advances in Rotor Performance and Wake Simulation Accuracy Using OVERFLOWNeal M. Chaderjian, Fundamental Modeling & Simulation Branch, NASA Ames Research Center
• 11/22/2011 A High-Fidelity Computational Framework For Nonlinear Fluid-Structure InteractionsKevin Guanyuan Wang, Ph.D. candidate,, Stanford University
• 11/08/2011 Hybrid Rockets for Solar System ExplorationAshley Chandler, Ph.D. candidate, Dept. of Aeronautics & Astronautics, Stanford University
• 11/01/2011 Mathematical Modeling of Wave Propagation and Scattering in Sandwich Composite Plates for Structural Health MonitoringVasyl Hafiychuk, SGT / NASA Ames Research Center
• 10/25/2011 High Fidelity CFD/CSD Rotorcraft Aeromachanics Prediction Using HeliosAndrew Wissink, U.S. Army Aeroflightdynamics Directorate, NASA Ames Research Center
• 10/18/2011 Defining Ablative Thermal Protection System Margins for Planetary Entry VehiclesIoana Cozmuta, Science & Technology Corp. / NASA Ames Research Center
• 10/11/2011 Engineering Risk Assessment for Space ExplorationDonovan Mathias, NASA Advanced Supercomputing Division, NASA Ames Research Center
• 10/04/2011 Energy Recovery From Waste Nitrogen Through N2O DecompositionYaniv D. Scherson, Ph.D. candidate, Dept. of Mechanical Engineering, Stanford University
• 09/28/2011 Computational Fluid Dynamic Simulations for the Launch EnvironmentJeffrey A. Housman, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 09/20/2011 Cubism in CFD: Activities and Research Directions in Automated Cartesian MethodsMichael J. Aftosmis, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 09/13/2011 Toward Planetary Entry Flow Control via Supersonic Retropropulsion (SRP) JetsNoël Bakhtian, Ph.D. candidate, Dept. of Aeronautics and Astronautics, Stanford University
• 09/06/2011 Aircraft Design with Active Load Alleviation and Natural Laminar FlowJia Xu, Ph.D. candidate, Department of Aeronautics and Astronautics, Stanford University
• 08/30/2011 The Role of Dual Consistency in Functional AccuracyJason Hicken, Postdoctoral Fellow, Dept. of Aeronautics and Astronautics, Stanford University
• 08/23/2011 Perspectives on Aerodynamic Shape OptimizationDavid Zingg, University of Toronto
• 08/16/2011 Acoustic Sources During Liftoff of a Launch Vehicle Insights from Recent TestsJayanta Panda, NASA Ames Research Center
• 08/09/2011 Challenges of Next-Generation Hybrid Rockets with Related Simulations and ModelingToru Shimada, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
• 08/01/2011 Cartesian Off-Body Grid Adaption for Viscous Time-Accurate Flow SimulationPieter Buning, NASA Langley Research Center
• 07/26/2011 Aircraft Drag Reduction through Extended Formation FlightAndrew Ning, Ph.D. Candidate, Department of Aeronautics & Astronautics, Stanford University
• 07/19/2011 Mars Probe TPS Performance and Aerothermal ReconstructionTodd White, ERC, Inc. / Aerothermodynamics Branch, NASA Ames Research Center
• 07/12/2011 Modeling and Analysis of Plasmas Formed by Hypervelocity Impacts on SatellitesSigrid Close, Department of Aeronautics & Astronautics, Stanford University
• 06/07/2011 Adjoints With Automatic Differentiation: Parallel Computation And Programming Language FeaturesJean Utke, Argonne National Laboratory
• 05/31/2011 Base Heating Anomalies During Ares I-X Test FlightDmitry Luchinsky, Mission Critical Technologies Inc. / NASA Ames Research Center
• 05/24/2011 Modeling Aircraft Contrails and Emission Plumes for Climate ImpactsAlexander Naiman, Ph.D. Candidate, Department of Aeronautics & Astronautics, Stanford University
• 05/17/2011 A Fokker-Planck Model for Efficient Rarefied Gas Flow CalculationsPatrick Jenny, Institute of Fluid Dynamics, Swiss Federal Institute of Technology (ETH)
• 05/10/2011 Aerodynamics and Debris Transport for the Space Shuttle Launch VehicleStuart Rogers, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 05/03/2011 Meeting the Challenges of the Simulation of Fluid-Structure InteractionAlan Mueller, Chief Technology Officer of CD-adapco, Seattle Office
• 04/26/2011 Physics-based Modeling and Simulation in the Engineering Risk Assessment of Ares ITed Manning, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 04/19/2011 Advanced Hybrid Rockets for Future Space LaunchArif Karabeyoglu, President and CTO of Space Propulsion Group, Inc., Sunnyvale, CA
• 04/05/2011 Recent Developments in Overset Grid Software ToolsWilliam Chan, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 03/29/2011 CFD/CSD Computation of Dynamic Stall of a Helicopter RotorJasim Ahmad, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 03/23/2011 Physics Based Modeling for Stage Separation RecontactDmitry Luchinsky, Mission Critical Technologies Inc. / NASA Ames Research Center
• 03/15/2011 Applications of the Lattice-Boltzmann methods in AerospaceSwen Noelting, Managing Director, Aerospace, at Exa GmbH (part of Exa Corp.)
• 03/08/2011 Mesh Quality Effects on the Accuracy of Euler and Navier-Stokes Solutions on Unstructured MeshesAaron Katz, US Army, Aeroflightdynamics Directorate, NASA Ames Research Center
• 03/01/2011 Computational Fluid Dynamics in GPUsSteve Rennich, HPC Developer Technology Engineer, NVIDIA
• 02/22/2011 Analyses of the Ares I Launch Vehicle Stage Separation with Plume EffectsGoetz Klopfer, Applied Modeling & Simulation Branch, NASA Ames Research Center
• 02/15/2011 Parallel Adjoint Framework for Aerodynamic Shape Optimization of Component-Based GeometryMarian Nemec, STC Corp. / Applied Modeling & Simulation Branch, NASA Ames Research Center
• 02/08/2011 Hazards Induced by Breach of Liquid Rocket Fuel Tanks: Risks of Cryogenic H2-Ox Fluids ExplosionsEkaterina Ponizovskaya, NASA Ames Research Center
• 02/01/2011 Large Data Visualization with VisItHank Childs, Lawrence Berkeley National Lab
• 01/24/2011 A High-Order Discontinuous Galerkin Simulation of Flapping Wings Designed for Energetically Optimal FlightPer-Olof Persson, Department of Mathematics, University of California, Berkeley
• 01/19/2011 An Interactive-Boundary-Layer Method with Transition Prediction for Cartesian Euler SolversDavid Rodriguez and Peter Sturdza, Desktop Aeronautics, Palo Alto, CA