KSP/PC choice

[Tim Kröger]

Dear Lisandro,

On Mon, 23 Jul 2007, Lisandro Dalcin wrote:

> On 7/23/07, Tim Kröger <tim at cevis.uni-bremen.de> wrote:
>
>> > What kind of stabilization for advection and pressure are you using?
>> 
>> Streamline diffusion (for advection).  I am not aware of the
>> requirement to stabilize the pressure as well.
>
> Well, you need to stabilize pressure if you have a non div-stable
> finite element space (this happens when using linear, equal-order FE
> for both velocity and pressure). Surely you are using a stable FE.

I'm using Taylor-Hood tetrahedron elements.

> I'm not exactly sure what do you understand for 'streamline difussion'
> (is rathre general). But we normally use non div-stable FE pairs,
> formulated with SUPG/PSPG (the first for advection, the second for
> pressure) stabilization, as proposed by Tezduyar in many publications.

I think it's the same that I am using, but I am not sure.  Can you 
give me a helpful reference?

> If you are interested in trying the my solution, I can help you. But I
> cannot assert you will have good performance, specially in big 3D
> problems. Anyway, we are currently using it to simulate the flow
> around a racing car (Re=16e6) with about 600K nodes in 30 processors.

I'm currently trying Matt's suggestion (to use MUMPS).  (It seems not 
to easy to install MUMPS.)  Anyway, I would like to try your solution 
as well.  What would I have to do?

Best Regards,

Tim

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