[Gmsh] Subdividing high-order tetrahedral mesh into hexahedron robustly

Bruno Blais bruno.blais at polymtl.ca
Fri Jun 5 07:33:42 CEST 2020

Dear all,
I hope you are well.
I am trying to generate a pure hexahedral mesh to be used with deal.II
(where tets are not supported).

However, I regularly encounter negative jacobians in a very limited number
of elements (<5), which prevents me from simulating my geometry.

I have tried to force the jacobian from being positive by adding the
following parameters:
Mesh.ElementOrder = 2;
Mesh.HighOrderOptimize = 1;
This works very well for tet mesh and I can generate my mesh in a few
seconds. However, as soon as I add the decomposition into hexes:
Mesh.SubdivisionAlgorithm = 2
GMSH slows down to a crawl and the mesh is unable to be generated even
after 24h of meshing

I was wondering if there was a solution to my problem, since deal.II only
support hex meshes. Is it possible to first fully generate the tet mesh and
then subdivide it into hexahedron within GMSH? I would like to keep the
mapping in order to ensure that the added points are correctly mapped to
the geometry. I know there are tools outside (such as tethex) that can
achieve this, but I would prefer not to go down this route.



*Bruno Blais*
Ing., Ph.D.
Professeur Adjoint / Assistant Professor
Génie chimique / Chemical engineering
Bureau/Room: A-684.2.3
T: +1-514-340-4711, 4533

C.P. 6079, succ. Centre-ville
Montréal, QC
E-mail: bruno.blais at polymtl.ca <bruno.blais at polymtl.ca>
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