Automatic coarsening of three dimensional anisotropic unstructured meshes for multigrid applications

Youssef Mesri (1) , Hervé Guillard (2, 3) , Thierry Coupez (4)

1 IFPEN - IFP Energies nouvelles
2 PUMAS - Plasma, tUrbulence, Modeling, Approximation and Simulation
3 JAD - Laboratoire Jean Alexandre Dieudonné
4 CEMEF - Centre de Mise en Forme des Matériaux

This paper describes an algorithm designed for the automatic coarsening of three-dimensional unstructured simplicial meshes. This algorithm can handle very anisotropic meshes like the ones typically used to capture the boundary layers in CFD with Low Reynolds turbulence modeling that can have aspect ratio as high as 104. It is based on the concept of mesh generation governed by metrics and on the use of a natural metric mapping the initial (fine) mesh into an equilateral one. The paper discusses and compares several ways to define node based metric from element based metric. Then the semi-coarsening algorithm is described. Several application examples are presented, including a full three-dimensional complex model of an aircraft with extremely high anisotropy.

Keywords: Anisotropy; Boundary layers; CFD; Coarsening; Mesh generation; Multigrid algorithms; Tetrahedral meshes

Domains: Geophysics [physics.geo-ph]; Geophysics [physics.geo-ph]; Global Changes

Youssef Mesri, Hervé Guillard, Thierry Coupez. Automatic coarsening of three dimensional anisotropic unstructured meshes for multigrid applications. Applied Mathematics and Computation, 2012, 218 (21), p. 10500-10509. ⟨10.1016/j.amc.2012.04.014⟩. ⟨hal-00713134⟩