saving .vol format into .msh format

Main Forum Old-Forum - do not post here
1

Hi,
I would like to ask on how to save .vol mesh to gmsh native .msh either using any available python script or calling netgen in batchmode on terminal.

Regards

2

Hi,

the Netgen mesh has an Export() function.

from netgen.geom2d import unit_square

mesh = unit_square.GenerateMesh(maxh=0.1)
mesh.Export("export.msh","Gmsh Format")

There is a second implementation (according to the comment, gmsh v2.xx format) which can be used with

mesh.Export("export.msh","Gmsh2 Format")

Regards,
Christoph

3

I tried exporting this way and got the following error message:

Traceback (most recent call last):
File “merge.py”, line 69, in
mesh.Export (“newmesh.gmesh”)
TypeError: Export(): incompatible function arguments. The following argument types are supported:
1. (self: netgen.libngpy._meshing.Mesh, filename: str, format: str) → None

Invoked with: <netgen.libngpy._meshing.Mesh object at 0x10dc2c8b0>, ‘newmesh.gmesh’

Maybe it’s a syntax issue, but I could not discover where the Export() command is explained.

4

As said by Christoph, you need to specify either “Gmsh Format” or “Gmsh2 Format” as second argument.
Best
Christopher

5

Sorry - I discovered I was editing a copy of the file in question. python3 now runs to completion.

That said, when I load the .msh file into GLVis (GLVis.org) to view it, I get an error message about missing boundary attributes (using either Gmsh or Gmsh2). Is there an easy way to fix this in the merge.py file?

Ultimately I’m looking to generate a mesh that has 1-2 solids with different material attributes embedded into a third solid, in such a way that the mesh is concentrated at the material borders.