On Dec 15, 2011, at 1:56 PM, Matthew Knepley wrote: > On Thu, Dec 15, 2011 at 10:23 AM, Ravi Kannan <rxk at cfdrc.com> wrote: > Dear All, > > > > This is Ravi Kannan from CFD Research Corporation. Recently, we are > experimenting with the BoomerAMG preconditioner for some ?stiff? CFD > problems. In that regard, all the other standard solver-preconditioner > combinations failed for the current CFD problem. The boomer is the only one > which is able to provide with ?converged? solutions. > > > > We noticed that the scalability of this boomer preconditioner is really poor. > For instance, even with a cell size of 2 million, we cannot scale to even 16 > partitions (in contrast, the other solver-preconditioner combinations like > the BI-CGS/BJacobi gave good enough scalability). > > > > Are we missing something? Do we need to use a more latest version of boomer? > > > Have you tried -pc_type gamg in petsc-dev?
For gamg you also want to use MPIAIJ matrices and set the block size MatSetBlockSize(mat,3), for a 3D velocity field, for instance. You can also try '-pc_gamg_type pa' or '-pc_gamg_type sa'. "pa", for plain aggregation might be better for CFD problems. Mark > > Matt > > Thanks, > > Ravi. > > > > > > -- > 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20111215/cee5b093/attachment.html>
