[petsc-users] parallel dual porosity

[Matthew Knepley]

On Wed, May 29, 2019 at 10:38 PM Adrian Croucher <a.croucher at auckland.ac.nz>
wrote:

> hi
> On 28/05/19 11:32 AM, Matthew Knepley wrote:
>
>
> I would not do that. It should be much easier, and better from a workflow
> standpoint,
> to just redistribute in parallel. We now have several test examples that
> redistribute
> in parallel, for example
>
>
> https://bitbucket.org/petsc/petsc/src/cd762eb66180d8d1fcc3950bd19a3c1b423f4f20/src/dm/impls/plex/examples/tests/ex1.c#lines-486
>
> Let us know if you have problems.
>
> If you use DMPlexDistribute() a second time to redistribute the mesh,
> presumably it will first delete all the partition ghost cells created from
> the initial distribution (and create new ones after redistribution).
>
> Hmm, I had not thought about that. It will not do that at all. We have
never rebalanced a simulation
using overlap cells. I would have to write the code that strips them out.
Not hard, but more code.
If you only plan on redistributing once, you can wait until then to add the
overlap cells.

> If I have also used DMPlexConstructGhostCells() to create boundary
> condition ghost cells on the distributed mesh, what happens to them when I
> redistribute? Do they get copied over to the redistributed mesh? or is it
> better not to add them until the mesh has been redistributed?
>
> Same thing here. Don't add ghost cells until after redistribution.

If you want to redistribute multiple times, again we would need to strip
out those cells.

  Thanks,

    Matt

> - Adrian
>
> --
> Dr Adrian Croucher
> Senior Research Fellow
> Department of Engineering Science
> University of Auckland, New Zealand
> email: a.croucher at auckland.ac.nz
> tel: +64 (0)9 923 4611
>
>

-- 
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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