Unstructured Meshing Strategies for Hypersonic Re-entry Flows

Unstructured grid generation is a major area of interest in the field of fluid dynamics due to its potential for rapid meshing of complex geometries. The hypersonics community has traditionally relied on structured hexahedral meshes due to their ability to resolve strong shockwaves when appropriate shock-fitting techniques are used. However, creating structured meshes for real-world flight vehicles with curvatures, protrusions, and other complexities can be prohibitively time-consuming and in some cases topographically impossible. In this study, we examine the potential of unstructured meshes for efficiently resolving flow fields in the wake, the bow shock, and the boundary layer of a hypersonic re-entry vehicle, taking into consideration cell type and size and applying cell clustering methods including shock fitting and shock capturing. These studies are carried out under both ideal gas and non-equilibrium flow conditions and compared to experimental data. The results suggest useful guidelines for efficiently meshing complex hypersonic flowfields.