[petsc-users] DMPlex and Boundary facets

[Matthew Knepley]

On Wed, May 19, 2021 at 12:46 PM Karin&NiKo <niko.karin at gmail.com> wrote:

> Thanks, I think I understand.
> So at the moment, the user has to manage the link between the labels of
> the different strata and the names.
>

Yes.


> I am mainly willing to use DMPlex  for  AMR  and names of groups are
> essential in our code - reading what Mat says
> gives me the impression that this is doable.
>

I think it is. I will be able to do it in the middle of June if you do not
have something by then. Can you make an issue?

  Thanks,

      Matt


> Thanks again,
> Nicolas
>
> Le mer. 19 mai 2021 à 16:02, Matthew Knepley <knepley at gmail.com> a écrit :
>
>> On Wed, May 19, 2021 at 9:57 AM Karin&NiKo <niko.karin at gmail.com> wrote:
>>
>>> Thank you very much Lawrence.
>>> Are the names lost or are they saved somewhere ?
>>> If I do : "./ex2 -filename /tmp/test/Cube_with_facets.msh4 -dm_view
>>> vtk:/tmp/foo.vtk" , I only get the tets of the initial mesh.
>>>
>>
>> Yes, the names are lost. Jed, Lisandro and Stefano have also asked me
>> about this. I have not done since everything is currently done by
>> number in Plex. It would involve either
>>
>> a) making a separate table in the DM which translates names to numbers
>>
>> or
>>
>> b) putting such a translation table in the DMLabel itself
>>
>> I am putting it off because doing some short is not hard, but getting it
>> to work with everything else would be somewhat of a pain.
>> It would need to distribute properly, propagate to
>> refined/coarsened/subset meshes, etc. which labels currently do. It would
>> not
>> be properly passed on when you just set an int on a point. I think it
>> will happen eventually, but I don't think I have time in the next
>> few weeks.
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Thanks,
>>> Nicolas
>>>
>>> Le mer. 19 mai 2021 à 15:49, Lawrence Mitchell <wence at gmx.li> a écrit :
>>>
>>>>
>>>>
>>>> > On 19 May 2021, at 14:46, Karin&NiKo <niko.karin at gmail.com> wrote:
>>>> >
>>>> > Dear Matthew,
>>>> >
>>>> > You are (again) right. This Gmsh test file is "dirty" : some
>>>> triangles do not belong to tests. Sorry for that.
>>>> > I have tried with another geo file (which is clean in that sense) and
>>>> PETSc reads with no error.
>>>> >
>>>> > I take this opportunity to ask my initial question : are the labels
>>>> of the Physical Entities saved somewhere ?
>>>> > A gmsh test file with several Physical entities is attached to this
>>>> email.
>>>>
>>>> Yes, plex represents Physical entities as "labels". In particular, for
>>>> facets, they are loaded as the "Face Sets" label, plex also loads markers
>>>> on cells in the "Cell Sets" label.
>>>>
>>>> e.g. here's the DMView output of your mesh.
>>>>
>>>> DM Object: DM_0x84000000_0 1 MPI processes
>>>>   type: plex
>>>> DM_0x84000000_0 in 3 dimensions:
>>>>   0-cells: 64
>>>>   1-cells: 279
>>>>   2-cells: 378
>>>>   3-cells: 162
>>>> Labels:
>>>>   celltype: 4 strata with value/size (0 (64), 6 (162), 3 (378), 1 (279))
>>>>   depth: 4 strata with value/size (0 (64), 1 (279), 2 (378), 3 (162))
>>>>   Cell Sets: 1 strata with value/size (7 (162))
>>>>   Face Sets: 6 strata with value/size (3 (18), 6 (18), 2 (18), 5 (18),
>>>> 1 (18), 4 (18))
>>>>
>>>>
>>>> Lawrence
>>>
>>>
>>
>> --
>> 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/>
>>
>

-- 
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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