Towards an Immersed Boundary Method with Viscous Wall Model

Speaker: Christoph Brehm, University of Kentucky
May 3, 2018

Presentation

Abstract

Immersed 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. While many immersed boundary approaches have been developed, there remains one key challenge that has yet to be solved. The primary shortcoming of Cartesian mesh immersed boundary methods is the inability of efficiently resolving thin turbulent boundary layers encountered in high-Reynolds number flow applications. The inefficiency of resolving this thin region of the flow is associated with the use of constant aspect ratio Cartesian grid cells. Conventional CFD approaches can efficiently resolve the large wall-normal gradients by employing grid stretching towards the wall thereby creating large aspect ratio cells near the wall. 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. This work was conducted in conjunction with Dr. Browne (University of Kentucky) and Dr. Ashton (University of Oxford).

Biography

Brehm joined the Mechanical Engineering Department of the University of Kentucky (UK) as an Assistant Professor in 2016. Previously, he has worked as a senior research scientist for Science Technology Corporation in the Computational Aerosciences Branch at NASA Ames Research Center from 2012 to 2016. He has worked as a developer of the Launch Ascent and Vehicle Aerodynamics (LAVA) solver framework and has employed LAVA to study a wide range of unsteady fluid dynamics problems, such as rocket launch site, contra-rotating open rotor, jet impingement, etc. His current research is at the intersection of fundamental numerical methods development and large-scale physics applications. His most recent research has focused on simulating and analyzing transitional and turbulent flows for fundamental studies in laminar-turbulent transition, acoustics, and fluid-structure interaction.

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