[petsc-users] replacing Schur complement in pcfieldsplit

[Matthew Knepley]

On Wed, Jun 20, 2012 at 9:00 AM, Klaij, Christiaan <C.Klaij at marin.nl> wrote:

>
> In order to implement SIMPLE-type preconditioners for the
> incompressible Navier-Stokes equations (Elman e.a. JCP 227, 2008)
> using the PCFieldSplit framework, it looks like I need to replace
> inv(A00) by some cheap approximation
>
> 1) in the Schur complement
>

When you have a Schur FS, the '0' solver is this approximation.


> 2) in the L and/or U of the LDU factorization
>

You can use whatever PC you want for the solver mentioned above.


> 3) while keeping A00 in the D
>

I think what you want here is -pc_fieldsplit_real_diagonal.

I would be really nice to make a PETSc example that did SIMPLE. I was
going to do this, but if you do it first, I will put it in.

   Matt


> What would be the best way?
>
>
> dr. ir. Christiaan Klaij
> CFD Researcher
> Research & Development
> E mailto:C.Klaij at marin.nl
> T +31 317 49 33 44
>
> MARIN
> 2, Haagsteeg, P.O. Box 28, 6700 AA Wageningen, The Netherlands
> T +31 317 49 39 11, F +31 317 49 32 45, I www.marin.nl
>
>


-- 
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
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