Volume meshing surface meshes with intended holes.

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1

I have a surface mesh which has a hole. I looked around, but found no info on flags or special commands needed to process such meshes. To generate the volume mesh, I run the script:

import netgen.meshing as meshing
mesh = meshing.Mesh()
mesh.Load(“srfmsh_in_2.vol”)
mesh.GenerateVolumeMesh(meshing.MeshingParameters())
mesh.Save(“out_in.vol”)

The mesh (srfmsh_in_2.vol) seems clean - netgen doesn’t complain, and it is not a huge mesh (~63K faces). After ~1/2 hour, several notifications “start tetmeshing”, and many ‘Smooth Mesh’ steps noted in the gui pane . . . netgen dies. I include the output below.

Any pointers?

Regards,
Tim

NETGEN-6.2-dev
Developed by Joachim Schoeberl at
2010-xxxx Vienna University of Technology
2006-2010 RWTH Aachen University
1996-2006 Johannes Kepler University Linz
Including OpenCascade geometry kernel
optfile ./ng.opt does not exist - using default values
togl-version : 2
OCC module loaded
loading ngsolve library
NGSolve-6.2.1707-81-g909f6c6e
Using Lapack
Including sparse direct solver Pardiso
Including sparse direct solver UMFPACK
Running parallel using 4 thread(s)
importing NGSolve-6.2.1707-81-g909f6c6e
(should) load python file ‘script_2.py’
generate vol mesh

Meshing subdomain 1 of 1
Delaunay meshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
start tetmeshing
Traceback (most recent call last):
File “”, line 5, in
RuntimeError: Caught an unknown exception!
Finished executing script_2.py

2

Could you post the surface mesh somewhere so we can have a look? What do you mean by holes in the surface mesh? How shall they be volume meshed?

Best
Christopher

3

Christopher:

The file is attached.

Tim

4

Christopher:

The (apparent) answer to my question is that no flags or settings are needed by netgen to mesh a surface mesh with a hole, as with the file I sent you.

Although netgen didn’t tell me of mesh problems, nor did I see any problems using meshlab (but I don’t now much about either code); I used some code that cleans surface meshes. After doing that, I did get a volume mesh out of netgen.

I don’t know everything that ‘cleaning’ code does to the mesh, which is a concern - but that is my problem.

Thanks again,
Tim