AUTOMATIC VISCOUS BOUNDARY LAYER MESH GENERATION

High Reynolds number fluid flows have boundary layers at the wall. To automatically generate robust and valid boundary layer mesh for the simulations is still the bottleneck problem of computational fluid dynamics. Prisms/Tetrahedra hybrid mesh leads to significant savings in mesh size and solution costs. However, it's still difficult to generate prismatic elements of high quality within boundary layers of complex models. Previous advancing layers techniques sometimes lead to invalid meshes and poor quality elements at concave/convex ridges and sharp corners. To improve these situations, we present a strategy for automatically generating viscous boundary layer mesh. In this method, multiple growth directions at ridges and corners are well defined by the dihedral angles around the vertices and the growth heights are adjusted appropriately. Therefore, boundary layer mesh grows well at sharp corners, convex and concave ridges of the domain. We also decrease the number of global intersection checks by predefining the total growth heights before generating elements through one global check, which improves the efficiency of mesh generation. At the same time, we develop a 3D strategy of mesh size control to get a size uniform triangular mesh of the outer boundary of the boundary layer mesh, which is beneficial to generate far-field isotropic mesh of high quality. Finally, mesh examples and the viscous flow simulations including 2D and 3D are presented. In 3D, the hybrid mesh over the standard ONERA M6 and DLR-F6 configurations are generated with the present method. The numerical results agree very well with experiment data which indicates that the hybrid viscous meshes generated by the proposed method are effective and efficient.