CFD modeling of F-35 using hybrid unstructured meshes

Computational models for the F-35 were created using several mesh generation programs. One program, Gridgen, is commercially available and was used to create an inviscid mesh for the F-35. Inviscid mesh quality was improved using P-Opt, a parallel optimization-based mesh-smoothing program. P-VLI, developed at the University of Tennessee at Chattanooga, was used to insert viscous layers into the mesh produced by Gridgen. Viscous meshes were analyzed at a transonic speed with two CFD codes. Subdivision-based mesh refinement was performed, adapting to high gradient of pressure, velocity magnitude and helicity. Prism layer nodes were only used to compute spacing parameters based on pressure. Tetrahedral nodes were used to compute spacing parameters based on all three functions. The adapted mesh improved the accuracy of shocks for vortices present in the CFD solutions, but did not significantly improve the comparison of the surface pressure coefficients with experiment. Changes to spacial flux limiting improved the results. A second and third mesh adaptation was performed using pressure and helicity and all nodes were included in the calculation of the spacing field. Further improvements in the surface pressure coefficients were realized. A computational model for a hover configuration was created and analyzed to determine forces and moments resulting from ground effects.