[petsc-users] MG on fieldsplit

[Jed Brown]

Geometric multigrid needs more information than algebraic multigrid. It's a
fact or life. In exchange, it can often be more efficient.

You likely notice that algebraic multigrid applied directly to the Stokes
problem fails, so you need to do more anyway. If you are happy with the
performance of using FieldSplit and applying BoomerAMG (or PCGAMG, or PCML)
to the viscous (velocity-velocity) part, then use that. If you aren't happy
with it, then try other methods, but some of those will need more
information.

On Thu, Feb 2, 2012 at 10:04, gouarin <loic.gouarin at math.u-psud.fr> wrote:

> It is not hard to use multigrid on velocity if I provide the interpolation
> as I said in my first email and as you say here. But it is for me too
> intrusive because I have to do a special case to use a multigrid pcmg
> whereas I can use boomeramg easily. I don't know if what I say is clear ...
>
> The idea is to test many solvers on this problem.
>
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