Heat flux and wall temperature divergence
 

Dear all,

I would like to simulate just a simple heat transfer from a wall to the fluid.
When I impose the wall temperature in the thermal BC, everything is going fine.
However, when I impose a surface heat flux (W/m²), the wall temperature is diverging, or is converging towards a very high T (non-physical) when I'm using limiters.
I suppose this is due to the fact that my fluid is stagnant. And numerically, the soft has trouble to handle it.

I already refined my mesh. It's better, but I still have non-physical wall temperature.

Does anybody has a solution or a suggestion ?

Thanks in advance !

Remark : I have a cooling wall in the domain with the opposite heat flux, in order to be at equilibrium.

That's free convection?

Dear Ardali,

Thanks for your answer, which maked me verify something !

As the fluid is stagnant, it is free convection, indeed. That is why, I enabled the boussinesq approximation.
However, I didn't capture any convection, and as I said, the temperature was diverging.
In fact, I realized that the thermal expansion coefficient was set to 0... I suppose this the cause of the error.
I believed naivly that the Fluent Database would provide me some meaningfull value.

Sorry for this simple problem.

Best,

Mat