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
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