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chtMultiRegionSimpleFoam - Own Case

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Old   January 24, 2016, 06:38
Default chtMultiRegionSimpleFoam - Own Case
  #1
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Hi,

I am working with OpenFoam since last August and used it for Lagrangian particle tracking and incompressible cases.
Now I want to move on. My topic of my Masterthesis is a simulation of a hot wire application in the exhaust side of a fuel cell.
However, this wire is hot (~180C constant temperature) and I want to figure out how the heat transfer to the fluid is, dependent on its composition.
Therefore I decided that chtMultiRegionSimpleFoam is the way to go. I started up with the heat exchanger case and the planeWall2D case.

So my case consists of tow blocks:
1. Solid block that should be hot (red block in the figure)
2. Fluid block with inlet and outlet (blue block in the figure, second figure shows position of inlet and outlet)

The meshing works, I did it based on snappyHexMesh, as I want to use that for my real project.

I am failing now at setting up the boundaries. Before coming to the real boundaries the big question is which files do I need to simulate this a case?

In 0/solid:
- T (temperature)

in 0/flow:
- p
- p_rgh
- T
- U

In both folders is as well the file "cellToRegion". Do I need that?

When my case finally works, I would like to upload it here, as I know there is a high interest in this solver, but it is as well a pain in the a** to set up.


Thank you! Hoping for an answer.

Best
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Old   January 25, 2016, 12:44
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  #2
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Hi,

I set up boundaries as far as I could until now. Now I have a problem with the temperature files. When I start my simulation it crashes after solving the velocity and gives this error:

Code:
Time = 1


Solving for fluid region flow
DILUPBiCG:  Solving for Ux, Initial residual = 1, Final residual = 0.009170221, No Iterations 1
DILUPBiCG:  Solving for Uy, Initial residual = 1, Final residual = 0.006990952, No Iterations 1
DILUPBiCG:  Solving for Uz, Initial residual = 1, Final residual = 0.01200734, No Iterations 1


-->FOAM FATAL ERROR: 
Attempt to cast type zeroGradient to type compressible::turbulentTemperatureCoupledBaffleMixed

    From function refCast<To>(From&)
    in file /home/openfoam/OpenFOAM/OpenFOAM-3.0.1/src/OpenFOAM/lnInclude/typeInfo.H at line 114.

FOAM aborting

#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::error::abort() at ??:?
#2  Foam::compressible::turbulentTemperatureCoupledBaffleMixedFvPatchScalarField::updateCoeffs() at ??:?
#3  Foam::mixedFvPatchField<double>::evaluate(Foam::UPstream::commsTypes) at ??:?
#4  Foam::mixedEnergyFvPatchScalarField::updateCoeffs() at ??:?
#5  Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>::GeometricBoundaryField::updateCoeffs() at ??:?
#6  Foam::fvMatrix<double>::fvMatrix(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::dimensionSet const&) at ??:?
#7  ? at ??:?
#8  ? at ??:?
#9  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#10  ? at ??:?
Aborted (core dumped)
Now there must be something rotten in the temperature boundaries...I compared it with the planeWall2D case and I am sure that I used the same boundary condition as there.

The T file for the fluid (called flow):
Code:
internalField   uniform 300;

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 300;
    }
    outlet
    {
        type            zeroGradient;
        value           uniform 0;
    }
    walls
    {
        type            zeroGradient;
        value           uniform 300;
    }
    flow_to_heater
    {
        type            compressible::turbulentTemperatureCoupledBaffleMixed;
        value           uniform 400;
        neighbourFieldName T;
        kappa           fluidThermo;
        kappaName       none;
        Tnbr            T;
    }
}
The T file for the solid (called heater):
Code:
internalField   uniform 400;

boundaryField
{
    inlet
    {
        type            zeroGradient;
        value           uniform 400;
    }
    outlet
    {
        type            zeroGradient;
        value           uniform 400;
    }
    walls
    {
        type            zeroGradient;
        value           uniform 400;
    }
    heater_to_flow
    {
        type            zeroGradient;
        value           uniform 400;
    }
    flow_to_heater
    {
        type            compressible::turbulentTemperatureCoupledBaffleMixed;
        neighbourFieldName T;
        kappa           solidThermo;
        kappaName       none;
        value           uniform 400;
    }
}
Has anyone an idea or a suggestion, what I messed up there ?

Thank you very much!

Best
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Old   January 25, 2016, 13:24
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Karl Lindqvist
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Dear Gerrit,
Your question regarding boundary conditions was answered here previously on this forum - the interface patch must be specified consistently for both regions.

For the files, OpenFOAM will quickly tell you if any files are missing once you try running the solver. I believe a (dummy) pressure file is needed in the solid region. The cellToRegion files are superfluous as far as I know since the actual grid is stored in the constant/<region>/polyMesh folder.

Best regards,
Karl
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Old   January 25, 2016, 15:09
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Hey Karl,

thanks for the answer! I did a really stupid mistake: I inserted the wrong patch name ..

However, now I can at least run the case some iterations until it breaks up. I will try to figure that out as well!

Thanks for the help!

Greetings to Norway from Denmark!

Best
Gerrit
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Old   January 27, 2016, 09:50
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Hi,

my case is running now. I hope someone else can use it as well to learn how to run this kind of simulations. If there are any questions or critics, please let me know - I will try to respond to this.

By the way: I used OpenFOAM 3.0.1.

Best
Gerrit
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