[petsc-users] Ghost points in DMSwarm

[Matthew Knepley]

On Fri, Feb 23, 2024 at 5:14 PM MIGUEL MOLINOS PEREZ <mmolinos at us.es> wrote:

> Dear all, I am struggling on how to include ghost points in DMSwarm local
> vectors. According to PETSc documentation it seems “straightforward” for a
> DMDA mesh. However, I am not so sure on how to do it for a DMSwarm. In
> fact, if I add the result
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> Dear all,
>
> I am struggling on how to include ghost points in DMSwarm local vectors.
> According to PETSc documentation it seems “straightforward” for a DMDA
> mesh. However, I am not so sure on how to do it for a DMSwarm. In fact,
> if I add the result of DMSwarmGetLocalSize for each rank, the result is
> the exact number of particles in the system. Which means that the halo is
> zero.
>
> Since there is a function called DMSwarmCreateLocalVectorFromField,I was
> wandering if there is a function already implemented in petsc (and I’m
> missing it) to include ghost points in DMSwarm and therefore don’t have
> to reinvent the wheel. If so, is there any example out there I can follow?
>

DMSwarm is currently different from the other DMs. There is no idea of
identity for particles, so there is no idea of a shared particle. You can
create this by adding an ID to your particle fields, but it would be a
manual process. DMSwarmMigrate() can duplicate particles if you have an
overlapping mesh, which would mimic shared particles.

  THanks,

     Matt


> Thanks in advance.
>
> Regards,
> Miguel
>
> petsc.org
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>
>

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