[petsc-dev] Algebraic Multigrid

[Mark Adams]

On Mon, Jul 25, 2016 at 6:17 PM, Ari Rappaport <arir at vosssci.com> wrote:

> Hi there!
> I am a student intern at Voss Scientific, a contractor for national labs.
> I have been researching multigrid methods this summer. My office has an
> established particle code which uses petsc libraries for matrix solutions.
> There is an interest in using multigrid methods to precondition our
> matrices. We have attempted to use the Algebraic Multigrid Preconditioner
> on our field solver and it was quite effective with one processor. However,
> when we moved to four processors the PCAMG took about 1000 times as many
> iterations.


Do you mean PCGAMG?


> I am wondering if there are any special considerations that need to be
> made for using AMG on multiple domains which in turn means multiple
> processors? Also, I understand there is also a PCMG option that takes
> advantage of the actual grid structure of the problem. I am also wondering
> if this could improve preconditioning.
>
> Thanks,
> Ari
>
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