[petsc-users] How to combine different element types into a single DMPlex?

[Eric Chamberland]

Hi,

On 2021-07-14 3:14 p.m., Matthew Knepley wrote:
> On Wed, Jul 14, 2021 at 1:25 PM Eric Chamberland 
> <Eric.Chamberland at giref.ulaval.ca 
> <mailto:Eric.Chamberland at giref.ulaval.ca>> wrote:
>
>     Hi,
>
>     while playing with DMPlexBuildFromCellListParallel, I noticed we
>     have to
>     specify "numCorners" which is a fixed value, then gives a fixed
>     number
>     of nodes for a series of elements.
>
>     How can I then add, for example, triangles and quadrangles into a
>     DMPlex?
>
>
> You can't with that function. It would be much mich more complicated 
> if you could, and I am not sure
> it is worth it for that function. The reason is that you would need 
> index information to offset into the
> connectivity list, and that would need to be replicated to some extent 
> so that all processes know what
> the others are doing. Possible, but complicated.
>
> Maybe I can help suggest something for what you are trying to do?

Yes: we are trying to partition our parallel mesh with PETSc functions.  
The mesh has been read in parallel so each process owns a part of it, 
but we have to manage mixed elements types.

When we directly use ParMETIS_V3_PartMeshKway, we give two arrays to 
describe the elements which allows mixed elements.

So, how would I read my mixed mesh in parallel and give it to PETSc 
DMPlex so I can use a PetscPartitioner with DMPlexDistribute ?

A second goal we have is to use PETSc to compute the overlap, which is 
something I can't find in PARMetis (and any other partitionning library?)

Thanks,

Eric


>
>   Thanks,
>
>       Matt
>
>     Thanks,
>
>     Eric
>
>     -- 
>     Eric Chamberland, ing., M. Ing
>     Professionnel de recherche
>     GIREF/Université Laval
>     (418) 656-2131 poste 41 22 42
>
>
>
> -- 
> 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/>

-- 
Eric Chamberland, ing., M. Ing
Professionnel de recherche
GIREF/Université Laval
(418) 656-2131 poste 41 22 42

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