[petsc-users] DMPlex and Boundary facets

[Karin&NiKo]

Sure! I send you both, one with the facets and one without.

Thanks,
Nicolas

Le mar. 18 mai 2021 à 17:49, Matthew Knepley <knepley at gmail.com> a écrit :

> On Tue, May 18, 2021 at 8:18 AM Karin&NiKo <niko.karin at gmail.com> wrote:
>
>> 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) ?
>>
>
> Can you also send the *.msh file? I do not have Gmsh on this machine.
>
>   Thanks,
>
>      Matt
>
>
>> Thanks for your help,
>> Nicolas
>>
>>
>>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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