[petsc-dev] [petsc-maint #57017] Hypre

[Jed Brown]

On Wed, Dec 1, 2010 at 15:44, Laurent Michel <laurent.michel at epfl.ch> wrote:

> You can find all the details about the problem I am solving in attachment.
>

Do you know Guillaume Jouvet (recent graduate at EPFL, worked on a similar
problem)?

It is unlikely that BoomerAMG will work for this problem, ILU will be very
sensitive to ordering.  Since you use equal-order velocity and pressure
spaces, your best bet for purely algebraic solvers is to interlace the
fields (u0,v0,w0,p0,u1,...) and use a solver that respects these blocks (use
a BAIJ format or call MatSetBlockSize(A,4)).  I know people who claim
success using ML for these equal-order methods, as long as the block
structure is respected, but this method is fragile and fails completely in
some non-extreme cases.

Note that most glaciological applications require a pretty strong
conservation statement, and the P1-P1 GLS methods that you describe using
are notoriously bad at conservation, especially with the irregular geometry
and steep gradients in coefficients that occur in practice.

Basically, what I want to solve is a time-independent Stokes problem, non
> linear in the viscosity (for the moment, I solve a fixed point for this). I
> am using the finite element library of my research group. The mesh is
> generated with gmsh (btw would you have any advice for a free, parallel,
> easy-to-use mesher?)
>

No, I use Cubit, but it takes a long time to get a license.

Jed
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