The curl-curl operator is notoriously difficult because of the form of its nullspace that the AMG algorithms have to carefully take into account. >From what I understand, ML tries to do something intelligent about curl-curl, but as far as I know that requires going around the plain vanilla API that PETSc taps into. Also, currently there is no libMesh API to take in a nullspace and serve it to PETSc (or Trilinos?), although that's something that can be easily fixed.
Jed should be able to comment on the issues with curl-curl and AMG in more detail. Dmitry. On Thu, Sep 13, 2012 at 5:09 PM, Roy Stogner <[email protected]>wrote: > > On Thu, 13 Sep 2012, Derek Gaston wrote: > > > I haven't looked at that problem and don't know much about curl-curl > spaces... but if the matrix would respond to multigrid at all I highly > > recommend compiling PETSc with Hypre support and using: > > -pc_type hypre -pc_hypre_type boomeramg > > > > For problems where it works it can't be beat... > > "Where it works" is the tricky part. It seems to fly on the curl-curl > problem, which is great; it failed to converge on a navier-stokes > problem I just tried, which rules it out as a default LIBMESH_OPTIONS > for me but still makes it a reasonable candidate for further > consideration... > > except that the very *first* time I tried PETSc with boomeramg, like 5 > years ago, it was "converging" to inaccurate answers on some of the > runs I tried. I'm 99% sure they'll have fixed whatever was wrong by > now, but once bitten twice shy... > --- > Roy > > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Libmesh-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/libmesh-users > ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://ad.doubleclick.net/clk;258768047;13503038;j? http://info.appdynamics.com/FreeJavaPerformanceDownload.html _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
