[mirmiyo]

In my model basically I have a fin which is cooled by water flow. Could you help me identify the problem?

I'm getting following error:
"Solving for fluid region fluid
DILUPBiCGStab: Solving for Ux, Initial residual = 0.82521303, Final residual = 0.051942511, No Iterations 3
DILUPBiCGStab: Solving for Uy, Initial residual = 0.87814371, Final residual = 0.075666319, No Iterations 3
DILUPBiCGStab: Solving for Uz, Initial residual = 0.75621016, Final residual = 0.054092061, No Iterations 11
DILUPBiCGStab: Solving for h, Initial residual = 0.81033778, Final residual = 0.078598853, No Iterations 12


--> FOAM FATAL ERROR: (openfoam-2012)
Negative initial temperature T0: -29.402764"

My boundary conditions are:
(U)
outlet
{
type pressureInletOutletVelocity;
value $internalField;
}
inlet
{
type flowRateInletVelocity;
massFlowRate 0.4;
extrapolateProfile yes;
value $internalField;
}

(p_rgh)
internalField uniform 1e5;

boundaryField
{
#includeEtc "caseDicts/setConstraintTypes"

".*"
{
type fixedFluxPressure;
value $internalField;
}
outlet
{
type fixedValue;
value $internalField;
}
}

(T)
boundaryField
{
#includeEtc "caseDicts/setConstraintTypes"

inlet
{
type fixedValue;
value $internalField;
}
topWall
{
type zeroGradient;
}
outlet
{
type inletOutlet;
value $internalField;
inletValue $internalField;
}
leftWall
{
type symmetryPlane;
}
rightWall
{
type symmetryPlane;
}
fluid_to_heatSink
{
type compressible::turbulentTemperatureCoupledBaffleMix ed;
value $internalField;
Tnbr T;
kappaMethod fluidThermo;
}
}

[saidc.]

Hi mirmiyo,
In my experience this error is usually caused by bad mesh. If you share your checkMesh results, you can find help easier. Also you should check your schemes too. You can try limit temperature.

Please check these posts.
chtMultiRegionFoam natural convection negative initial temperature
Negative initial temperature

Kind Regards,
Said.