[petsc-users] FieldSplit and Biot's poroelasticity

[Karin&NiKo]

Thank you very much for this preprint, Lawrence. I have also planned to use
the pressure mass matrix for the A11 block.

Unfortunately, at this time, I have no time for implementing things. What I
would like to do is to get the best out of the built-in methods of
fieldsplit/PETSc.

Any hint is welcome!

Nicolas

2016-12-13 19:02 GMT+01:00 Lawrence Mitchell <
lawrence.mitchell at imperial.ac.uk>:

>
>
> On 13/12/16 16:50, Karin&NiKo wrote:
> > Dear Petsc-gurus,
> >
> > I am solving Biot's poroelasticity problem :
> >  Images intégrées 1
> >
> > I am using a mixed P2-P1 finite element discretization.
> >
> > I am using the fieldsplit framework to solve the linear systems. Here
> > are the options I am using :
> > -pc_type fieldsplit
> > -pc_field_split_type schur
> > -fieldsplit_0_pc_type gamg
> > -fieldsplit_0_pc_gamg_threshold -1.0
> > -fieldsplit_0_ksp_type gmres
> > -fieldsplit_0_ksp_monitor
> > -fieldsplit_1_pc_type sor
> > -fieldsplit_1_ksp_type gmres
> > -pc_fieldsplit_schur_factorization_type upper
> >
> >
> > By increasing the mesh size, I get increasing numbers of outer
> > iterations.
> >
> > According to your own experience, among all the features of
> > fieldsplit, was is the "best" set of preconditioners for this rather
> > classical problem  in order to get an extensible solver (I would like
> > to solve this problem on some tens millions of unknowns of some
> > hundreds of procs)?
>
> Here's a recent preprint that develops a three-field formulation of
> the problem that gets reasonably mesh and parameter-independent
> iteration counts using block-diagonal preconditioning.
>
> https://arxiv.org/abs/1507.03199
>
> (No need for schur complements)
>
> If you can create the relevant blocks it should be implementable with
> -pc_fieldsplit_type additive
>
>
> Lawrence
>
>
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