[petsc-dev] Algebraic Multigrid

[Ari Rappaport]

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. 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