[elcino]

Good morning colleagues,

I want to simulate the natural convection inside a PC case which is using an heat sink to dissipate the heat produced by the CPU. The Pc is fan-less (no air is forced inside the case).

In the picture u can see the model. The CPU is under the heat sink (350000 w/m^2 which is 35 watts for a CPU with an area of 1 cm^2) and the heat sink is inside the case with the bottom and the top opened. Experiments shown that the maximum temperature is about 80 degrees celsius and the air reach a pretty fast speed just because of the natural convection.

I've tried to model it like this. Two domains, one solid and one fluid. The CPU is a wall with heat flow, the heat sink is the interface between the solid and the fluid and the case is suppose to be adiabatic. The PCB, the bottom wall of the solid domain, is also supposed adiabatic because is attached to the board with not real possibility to dissipate.

There's an inlet and an opening. I have good mesh division but the problem give me a fatal error and I can't make it converge.

Can someone help me?
I'm making some mistakes in the interface modeling?
Have I to model the convection in another way?

If I would like to use fluent, what I should do about the interface conditions??

Thanks for your time.