Mesh generation advices Code_Saturne website

[JulesL2]

Hi, I have found this document on Code_Saturne website Mesh_Generation and as it is not dated and referenced on Code_Saturne website, I have not found any information in the actual v7 guides, so are the information related on the mesh generation still valid ? More precisely, is it better to use quad based/hexa meshes or triangle based/tetra meshes with Code_Saturne ? I thought that hexa were better but in the document, it is stated that :

For RANS computations, at least, a good mesh consisting of tetrahedra (a fine mesh of equilateral tetrahedra) is a better choice than a mesh of hexahedra containing non-orthogonal cells.

Is this document up to date ? I get poor performances with tetrahedra whereas hexa meshes work nice

[YvanFournier]

Hello,

This document needs an update, in the sense that some approaches such as extruding the mesh at outlets or inserting boundary layer cells was not available upon its writing, but remains globally true.

• For RANS, tetrahedral meshes may be used, with some precautions (gradient algorithm selection, ...), but hexahedral meshes without too much warping are recommended if possible.
• For LES, a clean, hex-based mesh is highly recommended. We do have a Decaying Isotropic Turbulence test case with hex/tet comparisons, and are testing meshes where tetrahedra ar split into hexahedra (albeit not as regular as a classical hexahedral mesh), and testing which options can help those work, but a hex mesh is always preferred when possible.