KSP/PC choice

[Ben Tay]

Hi,

I am also trying to solve the NS eqns in 2d, finite volume mtd, using 
fractional step formulation.

I am currently using KSPBCGS and PCILU to solve the momentum eqn matrix 
and HYPRE's AMG and the default ksptype to solve the poisson eqn. Do you 
ppl think this is a good choice? Or is there a better recommendation?

Thank you.

Lisandro Dalcin wrote:
>> On Mon, 23 Jul 2007, Lisandro Dalcin wrote:
>> I think it's the same that I am using, but I am not sure.  Can you
>> give me a helpful reference?
>
> You can start here. This paper computes stab. params. using element
> mat and vecs, but you can also found explicit formulas (look for UGN
> subindices in formulas)
>
> http://www.mems.rice.edu/TAFSM/PUB_PRE/jALL/j89-CMAME-EBTau.pdf
>
>> I'm currently trying Matt's suggestion (to use MUMPS).  (It seems not
>> to easy to install MUMPS.)
>
> I istall MUMPS by letting PETSc to download and install it for me.
> Always worked.
>
>> Anyway, I would like to try your solution as well.  What would I have 
>> to do?
>
> First of all, you should move to the latest PETSc (2.3.3). Next, you
> have to be able to assemble a matrix of type MATIS. This implies you
> need to setup a ISLocalToGlobalMapping, by passing to it all local
> indices of degrees of freedom you have in the local processor.
> Once you have done this, you should be able to solve in parallel an
> small problem using PCJACOBI (jacobi, not block-jacobi).
>
> Next, mail me again. Using my preconditioner should then work out of
> the box. If you can confirm some gains, I would consider it to be
> added to PETSc.
>
> Regards,
>
>