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] wrote:
No, this does not work at all. The solver does not converge.
*Von:*Dumux [mailto:[email protected]] *Im
Auftrag von *[email protected]
*Gesendet:* Dienstag, 26. Mai 2015 15:47
*An:* [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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_______________________________________________________________
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>
_______________________________________________________________
_______________________________________________
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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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