[Gmsh] 3D recombination algorithm failure.

John Moore johnpmooreiv at gmail.com
Sat May 23 05:00:51 CEST 2015


Dear GMSH developers,

I used to be able to create quad-dominated meshes, but it seems that
something has changed and I can no longer get the 3D recombination
algorithm to work.

I've attached my test case, which is a simple cube in STEP file form.

Below is my GMSH script file:

Mesh.CharacteristicLengthFactor=0.5;
Mesh.CharacteristicLengthMax = 0.5;

Merge "UnitCube.stp";

Mesh.Algorithm = 8;
Mesh.Algorithm3D = 8;
Mesh.RecombineAll = 1;
Mesh.Recombine3DAll = 1;
// Mesh.RecombinationAlgorithm = 1;

I run gmsh with:

gmsh -3 Cube.geo

And get the following output:

Info    : 866 points 4131 edges and 1728 faces in the initial mesh
Info    : Found region 1
Info    : 0 points created - Worst tet radius is 4.24264 (PTS removed 0 0)
Info    : 3D point insertion terminated (1132 points created):
Info    :  - 1 Delaunay cavities modified for star shapeness
Info    :  - 0 points could not be inserted
Info    :  - 4123 tetrahedra created in 0.024102 sec. (171064 tets/sec.)
Info    : RECOMBINATION timing:
Info    :  --- CUMULATIVE TIME RECOMBINATION : 0 s.
Info    : RECOMBINATION CUMULATIVE STATISTICS:
Info    : .... Percentage of hexahedra   (#) : -nan
Info    : .... Percentage of hexahedra (Vol) : -nan
Info    : Done meshing 3D (0.214348 s)

If I just create a 2D surface mesh, everything works fine. Is this a
regression, or am I doing something wrong here?

Thanks,
John
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