[Gmsh] Node sets / groups

Geordie McBain gdmcbain at freeshell.org
Wed May 19 01:58:39 CEST 2010

2010/5/18 Olivier DESLANDES <deslandesolivier at orange.fr>:
> However, I don't find how defining node "physical groups" and writing it in
> a file.
> I kwnow how to define physical groups and writing it in file (i have defined
> "Physical Surface" and mesh with "Mesh 2;" then save with "Save
> "gmsh_model.msh";", so I have the numbers of my "physical surface" for
> elements but not for nodes).

The physical entities in Gmsh correspond to geometry rather than mesh,
so we have Physical Surfaces rather than `Physical Triangles',
Physical Volumes rather than `Physical Tetrahedra', and Physical
Points rather than `Physical Nodes'.  Do Physical Points do what you

> I have tried with .msh, .bdf and . med format and the physical group numbers
> appear for elements but not for nodes. I need these number for nodes also.

No, the .msh format doesn't have tags for nodes.  Some formats do; I
think this came up for MEDIT .mesh on this list recently, but the
problem was only one tag was permitted whereas a node can belong to
multiply Physical entities.  I don't know about .bdf or .med.

> Can you help me ?

I attach a simple example with Physical Points, but I don't know
whether it will completely solve your problem.  I think you'll still
need another work-around to deal with nodes not being taggable.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: gmsh_model.geo
Type: application/octet-stream
Size: 334 bytes
Desc: not available
URL: <http://www.geuz.org/pipermail/gmsh/attachments/20100519/3db7c532/attachment.geo>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: gmsh_model.msh
Type: model/mesh
Size: 2885 bytes
Desc: not available
URL: <http://www.geuz.org/pipermail/gmsh/attachments/20100519/3db7c532/attachment.msh>