Hi Max,
The heat source in that test is applied directly at the boundary of the
porous medium, so the value of the solid thermal conductivity at that
face influences the test result a lot. In the dumux version 2.12 we
applied a arithmetic mean for the calculation of the solid thermal
conductivity at each face. We now changed that to a harmonic mean so the
test results changed from the original paper. (you can find the
implementation at flux/box/fourierslawnonequilibrium.hh). Changing that
also changes the result and leads to more superheated steam in the
porous medium.
Does that help explain the results you observed?
Best wishes,
Katharina
On 3/11/19 9:27 PM, Maximilian Johannes Lueftner wrote:
Hi Bernd, hi Katharina,
yes, i changed the solid thermal conductivity in the outflow area
(0,1m to 10,1m) from 0,01 to at least 30.
I left the solid thermal conductivity in the area of interest (0m to
0,1m) unchanged at 30.
The heat flow is implemented at 0.1m. The changes I made concerning
the solid thermal conductivity relate only to the solid thermal
conductivity behind the heat source. Therefore, I wonder why just the
results with a solid thermal conductivity of greater than 0.2 provide
realistic results respectively superheating of the steam in the area
of interest.
I want to be able to expand this model, and therefore I have to fully
understand it.
Thank you in advance and best regards,
Max
Zitat von Katharina Heck <katharina.h...@iws.uni-stuttgart.de>:
Hi Max,
I am not sure if I get your question correctly. You are using the
mpnc-thermalnonequilibrium test and you change the solid thermal
conductivity in the outflow?
From what I understand about that test it would seem logical to me
that the solid thermal conductivity changes the results and also the
evaporation. The porosity is not high also in the outflow region
(0.35) so you have a relatively high ratio of solid material which
then influences the energy fluxes.
Can you maybe specify what you mean?
Best wishes,
Katharina
Hi Max,
I'm working with version 3.0 and have made the following changes.
> Old:
> using LinearSolver = Dumux::AMGBackend<TypeTag>;
auto linearSolver = std::make_shared<LinearSolver>(leafGridView,
fvGridGeometry->dofMapper());
> New:
> using LinearSolver = Dumux::UMFPackBackend;
auto linearSolver = std::make_shared<LinearSolver>();
> Is that correct?
Yes.
With these changes it is possible to calculate with more than 2000
elements, unfortunately the grading does not work.
Can you post the complete output?
But I have found that if the solid thermal conductivity in the outflow
area is increased to at least 0.2, superheated steam is calculated. If
the solid thermal conductivity is adjusted to the same value as the
porous area (30), the results will show a realistic behavior.
> Now I'm wondering, why the change in the solid thermal
conductivity in
the outflow area has such a big impact on the evaporation in the
porous area.
> Do you have any suggestions why that happens?
No, but maybe others can jump in who are more familiar with the
nonequilibrium models.
Kind regards
Bernd
Zitat von "Flemisch, Bernd" <bernd.flemi...@iws.uni-stuttgart.de>:
Hi Max,
you should first check if the problem is the linear solver by
switching to a direct solver. If you use Dumux 2.x, that's setting a
SET_TYPE_PROP(YourTypeTag, LinearSolver, UMFPackBackend<TypeTag>);
in the problem file, for 3.0 you have to change the corresponding
line in the main file.
Let us know how this changes things and we can decide what to do next.
Concerning the other issue about only one affected element, I'd
proceed as you and use a graded mesh to check if it spreads over
more elements once it's fine enough.
Kind regards
Bernd
On Thu, Mar 7, 2019 at 7:53 PM +0100, "Maximilian Johannes Lueftner"
<lueft...@mail.uni-paderborn.de<mailto:lueft...@mail.uni-paderborn.de>>
wrote:
Dear DuMuX experts,
i have adapted the simulation from the test folder
„dumux/test/porousmediumflow/mpnc/implicit/thermalnonequilibrium" .
I used the YASPGrid for 1D with grading:
struct Grid { using type =
Dune::YaspGrid<1, Dune::TensorProductCoordinates >; };
With 800 Elements (400 in the porous domain and 400 in the outflow)
and with 1600 Elements it works fin, but with more than 2000 Elements
I get the following error message:
Solve: M deltax^k = rNewton: Caught exception: "FMatrixError
[luDecomposition:/.../dumux/dune-common/dune/common/densematrix.hh:909]:
matrix is singular"
If I try it with grading I receive the following error message:
Solve: M deltax^k = rNewton: Caught exception: "NumericalProblem
[solveLinearSystem:/.../dumux/nonlinear/newtonsolver.hh:354]: Linear
solver did not converge"
Could you please help me to solve this problem? I tried it myself
several times but was not successful until now.
I suspect that an even finer grid is needed, since only in the last
element of the porous area does the temperature of the vapor increase
dramatically. Or does this behavior have a different reason? When the
heat flow is doubled, however, superheated steam is still calculated
only in the last element.
Thank you in advance and best regards,
Max
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_______________________________________________________________
Katharina Heck phone: +49 711 685 64719
IWS, Universität Stuttgart fax: +49 711 685 54719
Pfaffenwaldring 61 email:
katharina.h...@iws.uni-stuttgart.de
D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de
_______________________________________________________________
--
_______________________________________________________________
Katharina Heck phone: +49 711 685 64719
IWS, Universität Stuttgart fax: +49 711 685 54719
Pfaffenwaldring 61 email: katharina.h...@iws.uni-stuttgart.de
D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de
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