What is the best solver a poisson type eqn.

Matthew Knepley knepley at gmail.com
Fri Jun 12 09:37:54 CDT 2009

The problem is small enough that you might be able to use MUMPS.


On Fri, Jun 12, 2009 at 9:31 AM, Lisandro Dalcin <dalcinl at gmail.com> wrote:

> On Fri, Jun 12, 2009 at 11:13 AM, Christian
> Klettner<christian.klettner at ucl.ac.uk> wrote:
> > Sorry that I sent this twice. No subject in the first one.
> >
> > Dear PETSc Team,
> > I am writing a CFD finite element code in C. From the discretization of
> > the governing equations I have to solve a Poisson type equation which is
> > really killing my performance. Which solver/preconditioner from PETSc or
> > any external packages would you recommend? The size of my problem is from
> > ~30000-100000 DOF per core. What kind of performance would I be able to
> > expect with this solver/preconditioner?
> I would suggest KSPCG. As preconditioner I would use ML or
> HYPRE/BoomerAMG (both are external packages)
> > I am using a 2*quad core 2.3 GHz Opteron. I have decomposed the domain
> > with Parmetis. The mesh is unstructured.
> > Also, I am writing a code which studies free surface phenomena so the
> mesh
> > is continually changing. Does this matter when choosing a
> > solver/preconditioner? My left hand side matrix (A in Ax=b) does not
> > change in time.
> ML has a faster setup that BoomerAMG, but the convergence is a bit
> slower. If your A matrix do not change, then likely BoomerAMG will be
> better for you. In any case, you can try both: just build PETSc with
> both packages, then you can change the preconditioner by just passing
> a command line option.
> >
> > Best regards and thank you in advance,
> > Christian Klettner
> >
> Disclaimer: the convergence of multigrid preconditioners depends a lot
> on your actual problem. What I've suggested is just my limited
> experience in a few problems I've run solving electric potentials.
> --
> Lisandro Dalcín
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