KSP/PC choice

[gaatenek at irisa.fr]

Dear Tim,
I affraid that you have same memory problem while using MUMPS. I have
observed same memory problem while trying to solve some 3D Stokes
equations with MUMPS. I think the better way to solve this type of problem
is KSP with appropriate PC.
Regards,
Guy

> 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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> Dr. Tim Kroeger                            Phone +49-421-218-7710
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>
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