Unstructured and Hybrid Meshing
Hybrid Meshing with T-Rex
Pointwise's T-Rex (anisotropic tetrahedral extrusion) is an advancing layer technique for extruding regular layers of high-quality (right angle included) tetrahedra from boundaries. The algorithm adjusts to convex and concave regions and colliding extrusion fronts.
An optional step combines tetrahedra in the near-wall and near-wake regions into either prisms or hexahedra. The resulting mesh has a lower cell count than the raw tetrahedral mesh which improves computational efficiency. But this cell combination also creates higher quality cells in the regions where accuracy is most important.
This mesh around the Stanford Solar Car Project's vehicle was generated using T-Rex and includes prism (green) and tetrahedra (blue).
Classic Hybrid Meshing via Extrusion
Prism layers can also be generated via traditional extrusion methods that start with an unstructured surface mesh and follow normal, linear, rotational, or user-defined paths. Tunable controls let you adjust step size, mesh quality, and smoothing of the extruded layers.
Mixed Hex-Tet Meshes
Hexahedral and tetrahedral meshes can be interfaced in several ways to form a hybrid grid. Structured hexahedral and unstructured tetrahedral blocks can be indirectly interfaced by a point to point conformal interface with hanging edges. Direct hexahedral-tetrahedral interfaces are created through automatically generated pyramid cells.
Extruded prism blocks interface with tetrahedral blocks either directly (on the triangle faces) or through automatically generated pyramids (on the quadrilateral faces).
Tet Mesh Clustering with Sources
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.
A cone-shaped source was used to refine this mesh downstream of the nacelle.