[letoppina]

Hi, I am trying to simulate a solid body (tube walls) in contact with a fluid (water) with chtMultiRegionFaom solver. The solid walls are able to generate a heat flux (which should be homogeneously distributed within the thickness of the wall), thus giving isoflux conditions on the solid wall in contact with the fluid. This is my boundary condition (T) on my solid wall:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0/toptube";
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [ 0 0 0 1 0 0 0 ];

internalField   uniform 298.15;

boundaryField
{
    #includeEtc "caseDicts/setConstraintTypes"

    "maxY"
    {
        type            externalWallHeatFluxTemperature;

        mode            flux;
    heatsource    flux;

        Ta         uniform 298.15;  
                             
        q               uniform 100.0; // heat flux [W/m2]
        thicknessLayers (0.0006);  //solid wall thicnkess
        kappaLayers     (0.184);          // thermal conductivity of layer [W/m/K] 

        kappaMethod     solidThermo;

        value           $internalField;  // initial temperature [K]
    }   

    "(min|max)(X)"
    {
        type            zeroGradient;
       //value           $internalField;
    }

    "(min|max)(Z)"
    {
        type            empty;
        ~value;
    }

    "toptube_to_.*"
    {
        type            compressible::turbulentTemperatureCoupledBaffleMixed;
        value           $internalField;
        Tnbr            T;
        kappaMethod     solidThermo;
    }
}

And this is the boundary condition on the water (in contact with the tube):

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0/water";
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [ 0 0 0 1 0 0 0 ];

internalField   uniform 288.15;

boundaryField
{
    #includeEtc "caseDicts/setConstraintTypes"

    minX
    {
        type            fixedValue;
        value           $internalField;
    }
    maxX
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }
    "(min|max)(Z)"
    {
        type            empty;
        ~value;
    }
    "water_to_.*"
    {
        type            compressible::turbulentTemperatureCoupledBaffleMixed;
        value           $internalField;
        Tnbr            T;
        kappaMethod     fluidThermo;
    }
}

Technically, as the tube is exchanging heat flux with the water, the water should heat up. But on the simulation the heat flux dissipates immediately and the water becomes cold very soon. What am I doing wrong?