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 Dalc?n --------------- Centro Internacional de M?todos Computacionales en Ingenier?a (CIMEC) Instituto de Desarrollo Tecnol?gico para la Industria Qu?mica (INTEC) Consejo Nacional de Investigaciones Cient?ficas y T?cnicas (CONICET) PTLC - G?emes 3450, (3000) Santa Fe, Argentina Tel/Fax: +54-(0)342-451.1594
