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 hex-tet interfaces are created through automatically generated pyramid cells.

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Extruded prism blocks interface with tetrahedral blocks either directly (on the triangle faces) or through automatically generated pyramids (on the quadrilateral faces).

Prism layers are created by the extrusion of triangular surface grids following normal, linear, rotational, or user-defined paths with control over extrusion step size or aspect ratio.

Direct hex-tet interfaces are created through automatically generated pyramid cells.

SR-71

Read more about hybrid meshing in this article.