Unstructured grids consisting of triangles and tetrahedra are generated by a modified Delaunay method. Like structured grids, unstructured surface grids can span multiple entities in the geometry model and adhere to the CAD model automatically. The unstructured solver may be re-applied at any time, giving you control over minimum and maximum cell size, maximum cell-to-cell turning angle, maximum surface deviation, and boundary decay.

F-16

These attributes may also be set in advance to result in a good grid automatically. Edge swapping and LaPlace smoothing may also further improve unstructured surface grids.

Anisotropic Tetrahedral Extrusion

Unstructured meshes for viscous simulations with high aspect ratio near-wall cells for boundary layer resolution can now be generated automatically using Gridgen's anisotropic tetrahedral extrusion. Starting from a triangulated surface mesh, aniso extrusion creates layers of flat, included right-angle, tetrahedra that extrude orthogonally from the boundaries. The method includes mesh quality checks as well as local and global collision detection. Aniso extrusion is also available in the surface tri mesher.

This anisotropic tetrahedral mesh with viscous clustering to the aircraft surface was generated automatically.

An optional post-processing step combines a stack of three anisotropic tetrahedra into a single prism, reducing cell count and providing an even higher quality cell in the near-wall region.

Read this article about anistropic tetrahedral extrusion.