[petsc-users] DMPlex and Boundary facets

[Karin&NiKo]

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.
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.

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/>
>
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