[petsc-users] DMPlex and Boundary facets

[Karin&NiKo]

Dear PETSc team,

I have tried to load a test mesh available in Gmsh' s demos directory
 (share/doc/gmsh/demos/simple_geo/filter.geo, attached to this email) as a
DMPlex.
So I produced a msh4 file by doing :
        gmsh -3 filter.geo -o /tmp/test.msh4
Then I used src/dm/impls/plex/tutorials/ex2.c to load the mesh by doing :
        ./ex2 -filename /tmp/test.msh4

Unfortunately I get the error :

[0]PETSC ERROR: --------------------- Error Message
--------------------------------------------------------------
[0]PETSC ERROR: No support for this operation for this object type
[0]PETSC ERROR: Could not determine Plex facet for Gmsh element 1268 (Plex
cell 12681)

The error seems to come from the fact that the msh file contains tets *and*
facets *only on the Physical entities* (aka parts of the mesh boundary
where
the user will assign Dirichlet or Neuman conditions).
If I suppress these facets by commenting  the "Physical Surface" lines in
the geo file and regenerating the mesh, everything is fine.

But the use of these "Physical" stuff is very common in lots of finite
element codes in order to assign boundary conditions.
How should I do to keep  these boundary groups of 2D elements (with
corresponding names) ?

Thanks for your help,
Nicolas
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