[petsc-users] Creating dmplex in every rank and redistributing

[Matthew Knepley]

On Mon, Jul 4, 2022 at 2:29 AM Prateek Gupta <prateekgupta1709 at gmail.com>
wrote:

> Hi,
>
> Using dmplex, I am trying to create an example where I can start with a
> poor distribution of an unstructured mesh (reading from a file in parallel)
> and then use redistribution to optimize it.
>

You can call DMPlexDistribute() on any mesh, including a parallel one.


> I know that I can call ReBalanceSharedPoints on an already created
> distribution from dmplexDistribute. But is it possible to initialize a
> dmplex from each rank (each rank initializes its own chunk of the mesh) and
> then call this function?
>

Yes, this is done in


https://petsc.org/main/docs/manualpages/DMPLEX/DMPlexCreateFromCellListParallelPetsc/

It is not trivial to do by hand, so I would look at that code first if you
want to do that.


> Most of the numbering in dmplex DAG representation is local, but while
> reading from a file in parallel, I only have access to global numbering of
> nodes. Do I need to reassign this to a local numbering? Is there a
> datastructure within petsc that can help with this?
>
>
> Thank you.
> Sincerely,
> Prateek Gupta, PhD
>
-- 
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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