[zfaraday]

Dear foamers,

I'm in the need of some urgent help but I don't know if someone have the knowledge to help me. My problem is related to the createBaffles utility, more exactly when using it in parallel in a multi region case. I used to use it some months ago in order to create thermal baffles in a case that I finally refused because finally I created the baffles as a solid region instead. In that case I used to obtain some physical values for the thermal distribution in the baffles.

Now, after some work with the solid baffles, I tried to go back to the same case with thermal baffles created as a surface instead of as a solid. My surprise was that in the last iteration the temperature in the whole baffle remains constant with the same value as in the initial conditions.

Here comes the specification I use in my baffle's creation process:

baffles
{
    shieldBaffle1D_1_up
    {
        //- Use predefined faceZone to select faces and orientation.
        type        faceZone;//
        zoneName    shield_1_up;

        patchPairs
        {
            type            wall;
            patchFields
            {
                #include "./0.org/include/wallBafflePatches_shield"
                #include "./0.org/include/1DBaffle/1DTemperatureMasterBafflePatches_shield"
            }
        }
    }

and here are the include files:

"./0.org/include/wallBafflePatches_shield"

alphat
{
    type            compressible::alphatWallFunction;
    value           uniform 0;
}

epsilon
{
    type            compressible::epsilonWallFunction;
    value           uniform 0.01;
}

k
{
    type            compressible::kqRWallFunction;
    value           uniform 0.01;
}

mut
{
    type            mutkWallFunction;
    value           uniform 0;
}

p
{
    type            calculated;
    value           uniform 1e-2;
}

p_rgh
{
    type            fixedFluxPressure;
}

U
{
    type            fixedValue;
    value           uniform (0 0 0);
}
G
{
    type            MarshakRadiation;
    T               T;
    emissivityMode  lookup;
    emissivity      uniform 0.08;
    value           uniform 0;
}
IDefault
{
    type            greyDiffusiveRadiation;
    T               T;
    emissivityMode  lookup;
    emissivity      uniform 0.08;
    value           uniform 0;
}

"./0.org/include/1DBaffle/1DTemperatureMasterBafflePatches_shield"

T
{
    type   compressible::thermalBaffle1D<hConstSolidThermoPhysics>;

    thickness       uniform 0.002;  // thickness [m]
    Qr              Qr;
    relaxation      0;
    Qs              uniform 0;    // heat flux [W/m2]

    # include "1DbaffleSolidThermo_shield"

    value               uniform 500;
}

"1DbaffleSolidThermo_shield"

specie
{
    nMoles          1;
    molWeight       20;
}
transport
{
    kappa           21;//400ºC
}
thermodynamics
{
    Hf              0;
    Cp              460;
}
equationOfState
{
    rho             7930;
}

The specification I used in my old case was exactly the same as I used in the new one (it is exactly the same case, but some parts of the geometry have been slightly changed). The only thing I did in a different way is that in the current case I ran createBaffles utility in parallel whereas in the past I didn't. The only difference I noticed after the baffle creation process is in the "0/air/T" field (or "processor*/0/air/T" in the case of running the application in parallel), both files look a little different but they were supposed to be the same. Here you can see the boundary condition created by the utility looks slightly different in both cases...

    
Old case ---> "0/air/T"

shieldBaffle1D_1_up_master
    {
        type            compressible::thermalBaffle1D<hConstSolidThermoPhysics>;
        thickness       uniform 0.002;
        Qr              Qr;
        relaxation      0;
        Qs              uniform 0;
        specie
        {
            nMoles          1;
            molWeight       20;
        }
        transport
        {
            kappa           21;
        }
        thermodynamics
        {
            Hf              0;
            Cp              460;
        }
        equationOfState
        {
            rho             7930;
        }
        coupleGroup     shieldBaffle1D_1_up;
        value           uniform 600;
    }
    shieldBaffle1D_1_up_slave
    {
        type            compressible::thermalBaffle1D<hConstSolidThermoPhysics>;
        thickness       uniform 0.002;
        Qr              Qr;
        relaxation      0;
        Qs              uniform 0;
        specie
        {
            nMoles          1;
            molWeight       20;
        }
        transport
        {
            kappa           21;
        }
        thermodynamics
        {
            Hf              0;
            Cp              460;
        }
        equationOfState
        {
            rho             7930;
        }
        coupleGroup     shieldBaffle1D_1_up;
        value           uniform 600;
    }

    
Current case ---> "processor*/0/air/T"

shieldBaffle1D_1_up_master
    {
        type            compressible::thermalBaffle1D<hConstSolidThermoPhysics>;
        refValue        uniform 500;
        refGradient     uniform 0;
        valueFraction   uniform 0;
        value           uniform 500;
        sampleMode      nearestPatchFace;
        sampleRegion    air;
        samplePatch     shieldBaffle1D_1_up_slave;
        coupleGroup     shieldBaffle1D_1_up;
        thickness       uniform 0.002;
        Qs              uniform 0;
        specie
        {
            nMoles          1;
            molWeight       20;
        }
        equationOfState
        {
            rho             7930;
        }
        thermodynamics
        {
            Cp              460;
            Hf              0;
        }
        transport
        {
            kappa           21;
        }
        QrPrevious      uniform 0;
        Qr              Qr;
        QrRelaxation    0;
    }
    shieldBaffle1D_1_up_slave
    {
        type            compressible::thermalBaffle1D<hConstSolidThermoPhysics>;
        refValue        uniform 500;
        refGradient     uniform 0;
        valueFraction   uniform 0;
        value           uniform 500;
        sampleMode      nearestPatchFace;
        sampleRegion    air;
        samplePatch     shieldBaffle1D_1_up_master;
        coupleGroup     shieldBaffle1D_1_up;
        QrPrevious      uniform 0;
        Qr              Qr;
        QrRelaxation    0;
    }

At this stage I wonder if there is a known bug or something related to the parallel usage of the createBaffles utility in parallel or I am doing something wrong...

I will really appreciate any hint given in order to solve my little problem... Many thanks in advance!

Best regards,

Alex

[zfaraday]

Well... after another attempt I can state that it's not an issue about using the utility in parallel or not, because I have now run it normally and I still have the same problem... Any hint on what should I do so as to solve my problem?

For more information, I'm using chtMultiRegionSimpleFoam solver with frozenFlow option so that only enthalpy equation is solved. Furthermore, convection can be neglected (vaccum conditions, I set up a cp for the air of 10e-5) and only radiation and conduction must be taken into account in this case.

Hope someone can help me to set up properly the thermalBaffle1D BC.

Many thanks in advance.

Alex