Thanks. I was asking because I use PETSc+GMRES for RANS of turbulence and combustion (on unstructured grids). The most difficult problems don't get off the ground without a local LU preconditioner, but otherwise ASM+ILU or ILU(k) works OK for me.
- Karthik ----- Original Message ----- From: "Gaetan Kenway" <[email protected]> To: "Jed Brown" <jedbrown at mcs.anl.gov> Cc: "petsc-users" <petsc-users at mcs.anl.gov> Sent: Monday, April 29, 2013 7:25:11 PM Subject: Re: [petsc-users] Help with ML/BoomerAMG To Karthik Yes, GMRES is my nominal default. For systems that are easier to solve, TFQMR also seems to be competitive with GMRES. It is the high mach RANS problems with strong shocks shock induced flow separation that seem to give me the most trouble. Gaetan On Mon, Apr 29, 2013 at 10:07 PM, Gaetan Kenway < gaetank at gmail.com > wrote: That makes sense. Is there a reasonably easy way of doing that in PETSc currently for reasonably large systems? Gaetan On Mon, Apr 29, 2013 at 4:32 PM, Jed Brown < jedbrown at mcs.anl.gov > wrote: Gaetan Kenway < gaetank at gmail.com > writes: > I would be very interested in looking at the problematic eigenmodes as > well. On my end I use Tecplot for all my visualization. What sort of > visualization technique are you thinking about? Is it the KSP subspace > vectors you want to look at? No, it would be an eigensolve for either outliers or eigenvalues very close to zero. The cost to find the vector is like several solves, but it would tell us exactly what sort of functions are poorly approximated by the preconditioner. Then we would think about how we can change algorithms to make the preconditioner correct those functions better.
