[ivan_cozza]

Dear Foamers,

I'm working to simulate a CHT problem of an heat exchanger in which I have two fluids and one solid in between. One of the two fluids is periodic in longitudinal direction, and I want to simulate it using cyclic conditions,under the hypothesis of fully developed flow. I already simulated succesfully this problem using Star-ccm+ and Fully Developed Interfaces, so I am looking for a similar methodology.

Right now I'm using CHTMultiRegionSimpleFoam, and the periodic domain is simulated with the following bc:

boundary:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2206                                  |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    arch        "LSB;label=32;scalar=64";
    class       polyBoundaryMesh;
    location    "constant/Water_1/polyMesh";
    object      boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //


4
(
    DOWN_W_1
    {
        type            symmetry;
        nFaces          14128;
        startFace       2046784;
    }

    OUTLET_W_1
    {
        type            cyclicAMI;
        nFaces          4970;
        startFace       2060912;
        matchTolerance  0.0001;
        transform       translational;
        separationVector ( 0 0 0.00598 );
        neighbourPatch  INLET_W_1;
    }

    INLET_W_1
    {
        type            cyclicAMI;
        nFaces          4666;
        startFace       2065882;
        matchTolerance  0.0001;
        transform       translational;
        separationVector ( 0 0 -0.00598 );
        neighbourPatch  OUTLET_W_1;
    }

    Water_1_to_Solid
    {
        type            mappedWall;
        inGroups        1 ( wall );
        nFaces          110548;
        startFace       2070548;
        sampleMode      nearestPatchFace;
        sampleRegion    Solid;
        samplePatch     Solid_to_Water_1;
    }

)

0/T

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0/Water_1";
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [ 0 0 0 1 0 0 0 ];

initT 363.15;

internalField   uniform $initT;

boundaryField
{
    INLET_W_1
    {
        type            cyclicAMI;
    }
    OUTLET_W_1
    {
        type            cyclicAMI;
    }
    
    DOWN_W_1
    {
        type            symmetry;
    }
    Water_1_to_Solid
    {
        type            compressible::turbulentTemperatureRadCoupledMixed;
        // type            compressible::turbulentTemperatureCoupledBaffleMixed;
        value           uniform $initT;
        Tnbr            T;
        kappaMethod     fluidThermo;
        kappa           none;
    }
}

I'm setting the velocity with meanVelocityForce, and I'm trying to fix the temperature using a scalarSemiImplicitSourcein fvOptions file:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      fvOptions;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

momentumSource
{
    type            meanVelocityForce;

    selectionMode   cellZone;
	cellZone		Water_1;

    fields          (U);
    Ubar            (0 0 -1);
	relaxation		0.5;
}

heatSourceAbsorbed
{
	type scalarSemiImplicitSource;
	active true;
	selectionMode 	cellZone;
	cellZone		Water_1;
	volumeMode specific;
	injectionRateSuSp
	{
		h (1.0e+08 0); // kg/m/s^3
	}

}

limitT
{
    type            limitTemperature;
    active          yes;

    selectionMode   all;
    min             290;
    max             400;
}

Unfortunately this is blowing up in few iterations, as the temperature runs out to very low values. I expected that with this setup, being the fluid here linked to a solid which is itself linked to a fluid that has a standard inlet and outlet condition, this will be enough to determine the water temperature, but it seems not.

In Star-ccm+ Fully Developed Interface is possible to assign a cyclic temperature with a jump that is determined by the average value of T at inlet and the heat balance that is passing throug the domain walls. This is working fine in my case.

Is there some setup of bc that rpovide a similar setup?
I'm using OpenFOAM 2212.

Looking forward to get your answers!
Thanks and stay cool!
Ivan

[Alczem]

Hey


Not sure about setting up periodic flow, but chtMultiRegionSimpleFoam needs a fvOptions file per region, and it should be put inside system/fluid or system/solid and each fvOptions should contain only the options related to their region.


Also make sure your separationalVector in the boundary file is correct. Other than that, maybe check again some tutorials about channel simulation?


Good luck!