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Recent Developments on Automation of Overset Structured Mesh Generation

AMS Seminar Series

Speaker: William Chan, Andrew Chuen, Computational Aerosciences Branch, NASA Ames Research Center

Presentation

Seminar Slide Deck (PDF-26MB)

Abstract

A scheme is presented for the automatic generation of structured overset meshes on geometries that are defined by Boundary Representation (BRep) solids. The surface domain is automatically decomposed into face, edge and node meshes corresponding to the three basic BRep entity types. Grid point distribution is determined by geometric features as well as user-specified parameters on maximum stretching ratio, maximum turning angle, and maximum grid spacing scaled by component characteristic length. Hyperbolic or algebraic schemes are used to create the edge and node meshes with automatic estimates for the marching distances. Robustness of the hyperbolic surface marching method is improved by replacing the point projection step with a walking scheme. Optimal overlap between adjacent meshes is ensured by a loosely-coupled boundary condition for hyperbolic meshes. Domain connectivity is automatically performed on the surface mesh system. Near-body volume meshes are generated using hyperbolic methods with automatic selection of smoothing parameters based on concave region detection. Input files for flow solver boundary conditions and component aerodynamic loads computation are also automatically created. 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).

This work is supported by NASA ARMD’s T3 & RVLT projects.

Biography

Photo of William Chan
William Chan is a research scientist in the Computational Aerosciences Branch at NASA Ames Research Center. His primary interest is on the development of algorithm and software for pre-processing and post-processing of computational simulations using overset grids. He is the principal developer of many of the modules in the Chimera Grid Tools (CGT) software package which has been distributed to over 1000 organizations in U.S. government laboratories, industry and universities. Since joining NASA Ames, he has supported numerous NASA projects. These include high fidelity CFD simulations of the Space Shuttle Launch Vehicle, multiple subsonic, supersonic, and vertical-lift vehicles, various turbopumps and liquid rocket sub-systems, and a variety of space launch vehicles from the Constellation and Space Launch Systems Programs. His work has been recognized through the NASA Exceptional Achievement and Exceptional Service Medals, and various Technology Transfer awards. William obtained his B.S. in Mathematics from Southampton University in the U.K., M.S. and Ph.D. from the Mechanical Engineering Department of Stanford University. He is an Associate Fellow of the AIAA.

Photo of Andrew Chuen
Andrew Chuen is a NASA Pathways Intern in the Computational Aerosciencies Branch at NASA Ames Research Center. He is also currently a Ph.D. student under the advisement of Professor Mohamed Hafez in the Mechanical and Aerospace Engineering Department at the University of California, Davis. Prior to his doctoral studies, Andrew received his M.S. and B.S. degrees in Mechanical and Aerospace engineering at UC Davis. In his M.S. thesis, Andrew investigated non-uniqueness in two-dimensional compressible flows.