HydroGeoSphere/Tetrahedral Element Grids

Tetrahedra
Subdivides block elements into tetrahedra (4-node) elements. If the grid does not contain block elements the preprocessor will stop and you will be issued a warning.
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Block elements must be orthogonal or nearly so in order to avoid introducing numerical error, while tetrahedral elements can handle irregular geometries. The subdivision into tetrahedra is carried out by HydroGeoSphere during problem solution and is transparent to the user. Faces which can be designated as fracture elements are restricted to the original block elements. This is merely a matter of convenience and future versions may allow tetrahedral element faces to be designated as fractures.