[dune-pdelab] Nonoverlapping solver backend for implicit time-steppers

[Jared Okiro]

On 10/30/2012 11:41 AM, Steffen Müthing wrote:
> Hi Jared,
>
> what do you mean by parallelizing the system? I assume you ran this in parallel,
> and that's when the problems cropped up?
>
> Having said that, your example uses a nonoverlapping solver, not an overlapping
> one as per Christian's suggestion. For DG, that won't work just like that, as the
> per-processor domains are not coupled in any way (with nonoverlapping assembly,
> the processes only share DOFs with codim>  0, those attached to a Border entity in
> Dune-speak, and you don't have any DOFs of that type with a DG method). I'd suggest
> you switch to an overlapping method like Christian said.
>
> Apart from that, you cannot use the nonoverlapping Jacobi preconditioner here, as
> the nonoverlapping Jacobi implementation in PDELab currently is not block-aware
> and will thus not invert the dense DG blocks on the diagonal, but only the diagonal
> of those blocks.
>
> Steffen
>
> Am 30.10.2012 um 10:25 schrieb Jared Okiro:
>
>> On 10/19/2012 10:15 PM, Christian Engwer wrote:
>>> UG provides a ghost layer, which should be sufficient for overlamming
>>> parallelization using DG methods, as they are cell-based.
>>>
>>> regarding the edge communication and UG you have to be more specific,
>>> as "but it doesn't work for me" is not sufficient for us to guess what
>>> the problem might be.
>>>
>>> Christian
>>>
>>> On Fri, Oct 19, 2012 at 06:27:56PM +0200, Jared Okiro wrote:
>>>> Dear PDELab Members,
>>>>
>>>> I am solving a reaction-diffusion system with more than two
>>>> equations in 2D using
>>>> Interior Penalty DG methods on UG grid. The sequential version works
>>>> well, but if I try the parallel
>>>> version, I get the error "missing edge communication". I saw
>>>> sometime that edge communication was
>>>> implemented in UG but it doesn't work for me.  The linear solver
>>>> fails from the first iteration.
>>>> I am still new to DUNE and in particular parallel implementation. I
>>>> am inquiring if there is any example
>>>> available for Nonoverlapping solvers with implicit time integrators
>>>> which I can refer to. If not, then I will appreciate any advice.
>>>> Thank you.
>>>>
>>>> Kind regards,--
>>>>
>>>> Jared Ouma Okiro,
>>>> Institute for Analysis and Numerics,
>>>> Otto-von- Guericke Universität,
>>>> Universitätsplatz 02, Gebaude 02 / 115
>>>> 39106 Magdeburg, Germany
>>>> Office Tel: +493916712660
>>>> Fax:        +493916718073
>>>> Mobile:     +4917657479787
>>>> Home Tel:   +4939155917376
>>>>
>>>>
>>>> _______________________________________________
>>>> dune-pdelab mailing list
>>>> dune-pdelab at dune-project.org
>>>> http://lists.dune-project.org/mailman/listinfo/dune-pdelab
>>>>
>> Dear Christian,
>> Thank you for the information. I decided to do a test case for a scalar problem before parallelizing the system. Attached is the test case. In this test case only one time step is solved and one can see that
>> it produces the wrong solution at the processor boundaries.
>> I would be grateful for any further assistance.
>> Thank you.
>>
>> -- 
>> Jared Ouma Okiro,
>> Institute for Analysis and Numerics,
>> Otto-von- Guericke Universität,
>> Universitätsplatz 02, Gebaude 02 / 115
>> 39106 Magdeburg, Germany
>> Office Tel: +493916712660
>> Fax:        +493916718073
>> Mobile:     +4917657479787
>> Home Tel:   +4939155917376
>>
>> <nonlinearproblem.cc><nonlinearproblem.hh>_______________________________________________
>> dune-pdelab mailing list
>> dune-pdelab at dune-project.org
>> http://lists.dune-project.org/mailman/listinfo/dune-pdelab
> Steffen Müthing
> Universität Stuttgart
> Institut für Parallele und Verteilte Systeme
> Universitätsstr. 38
> 70569 Stuttgart
> Tel: +49 711 685 88429
> Fax: +49 711 685 88340
> Email: steffen.muething at ipvs.uni-stuttgart.de
>

Dear Steffen,
I have tried the overlapping version also. I followed the steps from 
example06 code in pdelab-howto and
did it for DG method, but still did not succeed. I have attached the files.
The linear solver fails to converge the solution.
I will appreciate further assistance.
Thank you.

-- 
Jared Ouma Okiro,
Institute for Analysis and Numerics,
Otto-von- Guericke Universität,
Universitätsplatz 02, Gebaude 02 / 115
39106 Magdeburg, Germany
Office Tel: +493916712660
Fax:        +493916718073
Mobile:     +4917657479787
Home Tel:   +4939155917376

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