Successful completion of our Phase I effort results in development and delivery of an enhanced version of HeldenMesh demonstrated for accurate, efficient, and automated CFD mesh generation for WMLES applications. HeldenMesh is an existing commercial CFD mesh generator already in widespread use in industry and NASA for generating meshes for Navier-Stokes CFD flow solvers like FUN3D and USM3D. It was originally developed under Helden internal research and recently enhanced under several NASA and Air Force Research Laboratory (AFRL) funded SBIR efforts. Our proposed effort builds upon these past efforts by incorporating two enhancements to enable more accurate and robust WMLES simulations. First, HeldenMesh is modified to generate a quad-dominated surface mesh and a hex-dominated near-wall layer mesh for a more efficient and accurate cell type which is more suited to WMLES analysis. Second, HeldenMesh is modified to generate wedge elements in the viscous layers at sharp trailing edges to improve the overall grid quality and grid normal alignment. Any further development required to improve HeldenMesh’s WMLES mesh generation capability is identified under Phase I and plans made for completion under a follow-on Phase II. With these enhancements in place, we then demonstrate the accuracy and efficiency of HeldenMesh for WMLES applications using the FUN3D flow solver on two test cases coordinated with NASA. As part of these demonstrations, WMLES meshing best practices are developed in terms of grid quality, impact of anisotropic stretching near and far from the wall vs. isotropic meshing, number of viscous layers, layer growth rate/profiles, as well as spanwise/chordwise spacing requirements in the critical near-wall regions. A grid convergence study is also performed with impact of cell count in critical regions vs. accuracy. Our effort culminates with delivery of an enhanced HeldenMesh executable with a direct FUN3D interface for independent testing.
The successful completion of this Phase I effort supports all NASA programs and projects that use CFD. HeldenMesh is already used extensively by NASA for generation of unstructured meshes and is already a key component of their CFD process. The technology developed under this project will enable design decisions by Aeronautics Research Mission Directorate (ARMD) and Human Exploration Operations Mission Directorate (HEOMD).
Helden Aerospace has already successfully transitioned its existing HeldenMesh commercial grid generator to industry. Grid quality improvements made under Phase I benefits users running WMLES and also the majority of users performing RANS simulations. This effort results in an improved product ready for widespread use by our growing base of industry users.