Ok. Can you try to use your multidomain setting, but just don't couple
by providing normal boundary conditions such as no-flux for each
subdomain also at the coupling interface? Does this work?
Since both SuperLU and Pardiso are direct solvers, I would not expect
that one can solve a system that the other one cannot. Pardiso should
work for the multidomain stuff and people that use it claim that it is
faster than SuperLU.
Bernd
On 05/27/2015 12:47 PM, [email protected] wrote:
Hi Bernd,
I already use SuperLU. Btw what about the PARDISO solver? Can it be
used for multidomain applications and could this be an improvement?
Kind regards
Georg
*Von:*Dumux [mailto:[email protected]] *Im
Auftrag von *Bernd Flemisch
*Gesendet:*Mittwoch, 27. Mai 2015 12:36
*An:* DuMuX User Forum
*Betreff:* Re: [DuMuX] Check for phase presence in the mpnc model
I don't understand why the linear solver should get into trouble by
this modification. What linear solver do you use? If you use an
iterative one, can you check if you run into an exception from the
preconditioner when compiling with debug options, and also
double-check by replacing the iterative solver with SuperLU?
Kind regards
Bernd
On 05/26/2015 04:50 PM, [email protected]
<mailto:[email protected]> wrote:
By “the solver” I mean the linear solver. At least the values are
correct. Maybe the numerical error from the coupling just gets too
high if I use the old solution?
Georg
*Von:*Dumux [mailto:[email protected]] *Im
Auftrag von *Bernd Flemisch
*Gesendet:* Dienstag, 26. Mai 2015 16:29
*An:* DuMuX User Forum
*Betreff:* Re: [DuMuX] Check for phase presence in the mpnc model
Strange. By "the solver", do you mean the Newton or the linear
solver? Can you check if the values in elemVolVarsPrev1/2 make sense?
Bernd
On 05/26/2015 03:53 PM, [email protected]
<mailto:[email protected]> wrote:
No, this does not work at all. The solver does not converge.
*Von:*Dumux [mailto:[email protected]]
*Im Auftrag von *[email protected] <mailto:[email protected]>
*Gesendet:* Dienstag, 26. Mai 2015 15:47
*An:* [email protected]
<mailto:[email protected]>
*Betreff:* Re: [DuMuX] Check for phase presence in the mpnc model
Hi Bernd,
That’s a good idea. I will try it and see what happens.
Kind regards
Georg
*Von:*Dumux [mailto:[email protected]]
*Im Auftrag von *Bernd Flemisch
*Gesendet:* Dienstag, 26. Mai 2015 15:44
*An:* DuMuX User Forum
*Betreff:* Re: [DuMuX] Check for phase presence in the mpnc model
Hi Georg,
you could try to check for the phase state depending on the
solution from the old _time_ step. If you have an
infrastructure similar to the current multidomain models, you
should have CParams which offer access to the old values via
elemVolVarsPrev1/2.
Kind regards
Bernd
On 05/26/2015 03:33 PM, [email protected]
<mailto:[email protected]> wrote:
Hi Bernd,
I checked for the phase presence in the evalCoupling
function of my localoperator-file. Here I couple the water
component balance of the mpnc model to my membrane model
by setting CouplingOutflow boundary conditions for the
membrane and CouplingInflow for the mpnc domain. As I
neglect miscibility in the membrane (I assume pure water
here), I set the activity of water in the membrane to 1 if
the liquid phase is present. Checking for the water
saturation for the phase presence caused numerical
problems which did not occur when I use the sum of mole
fractions in the liquid phase instead. Now that I write it
down it puzzles me even more… Anyway, the appearance of
the liquid phase during startup of a fuel cell combined
with the coupling to the membrane transport is numerically
really challenging and I need to work on this topic some
more. If I obtain some reliable results I will be glad to
share them with you.
King regards
Georg
*Von:*Dumux
[mailto:[email protected]] *Im
Auftrag von *Bernd Flemisch
*Gesendet:* Dienstag, 26. Mai 2015 15:06
*An:* DuMuX User Forum
*Betreff:* Re: [DuMuX] Check for phase presence in the
mpnc model
Hi Georg,
On 05/22/2015 08:24 AM, [email protected]
<mailto:[email protected]> wrote:
Hello DuMuX,
I started working with the mpnc model and I wonder how
I can check for the phase presence. Just accessing the
phase saturation does not seem to be a safe way since
during newton iterations the value may differ from
zero even though the phase is not present (am I right
here?). Right now I check if the sum of all mole
fractions in the phase of interest is equal to 1. This
seems to work, however I wonder whether I should
include a threshold (something like:
sumMolefractions[phaseIdx] > 1 – eps_). Or is there a
better way?
I am not sure if one criterion is better than the other.
Before the Newton converges, values for saturations can be
"wrong", but so can the values for the mole fractions. If
a solution at some Newton iteration shows a positive
saturation value, then the corresponding phase is present
for this solution. However, values may change for the
converged solution. So I would be careful with making
decisions based on intermediate solutions.
Can you describe in more detail what you mean by "This
seems to work"? Does it not work with checking the
saturation values?
Kind regards
Bernd
Thanks for your help
Georg Futter
——————————————————————————
*German Aerospace Center *(DLR)
Institute of Engineering Thermodynamics | Computational
Electrochemistry | Pfaffenwaldring 38-40 | 70569 Stuttgart
Dipl.-Ing. *Georg Futter* | Ph.D. student
Telefon 0711/6862-8135 | [email protected]
<mailto:[email protected]>
www.DLR.de <http://www.dlr.de/>
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<mailto:[email protected]>
D-70569 Stuttgart url:www.hydrosys.uni-stuttgart.de
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_______________________________________________________________
Bernd Flemisch phone: +49 711 685 69162
IWS, Universität Stuttgart fax: +49 711 685 60430
Pfaffenwaldring 61 email:[email protected]
<mailto:[email protected]>
D-70569 Stuttgart url:www.hydrosys.uni-stuttgart.de
<http://www.hydrosys.uni-stuttgart.de>
_______________________________________________________________
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--
_______________________________________________________________
Bernd Flemisch phone: +49 711 685 69162
IWS, Universität Stuttgart fax: +49 711 685 60430
Pfaffenwaldring 61 email:[email protected]
<mailto:[email protected]>
D-70569 Stuttgart url:www.hydrosys.uni-stuttgart.de
<http://www.hydrosys.uni-stuttgart.de>
_______________________________________________________________
_______________________________________________
Dumux mailing list
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--
_______________________________________________________________
Bernd Flemisch phone: +49 711 685 69162
IWS, Universität Stuttgart fax: +49 711 685 60430
Pfaffenwaldring 61 email:[email protected]
<mailto:[email protected]>
D-70569 Stuttgart url:www.hydrosys.uni-stuttgart.de
<http://www.hydrosys.uni-stuttgart.de>
_______________________________________________________________
_______________________________________________
Dumux mailing list
[email protected]
https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
--
_______________________________________________________________
Bernd Flemisch phone: +49 711 685 69162
IWS, Universität Stuttgart fax: +49 711 685 60430
Pfaffenwaldring 61 email: [email protected]
D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de
_______________________________________________________________
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