[MagicianOfChaos]

Good morning,

I need some help in order to understand better why in my model I get very high temperatures compared to temperatures measured in reality.
On ANSYS Electronics Desktop (Icepak design) I'm trying to solve the conjugate heat transfer due to natural convection between PCB and electrical components (which are inside a plastic case) and the air, both internal and external. I will share also some pictures to better calrify the situation.

23-01-2025-1737622857-mceclip4.png

The setup of the simulation is the following:

I built up a domain big enough to simulate natural convetion
I used 2 refinements for the mesh: a box that includes all the case, internal air, upper components ecc, and another box that includes only the PCB and the components mounted on the bottom.

Boundary conditions: all walls with fixed temperature (ambient temperature);
Initial Conditions: Vx = 0; Vy = 0.001 m/s (opposite to the gravity along -y); Vz = 0
Losses in [W] on different components using the "Block" model (the total dissipated power must be specified)

For the setup, I followed suggestions the "natural convection default", that is: the simulation is a steady-state, laminar flow, radiation is on (discrete ordinates model), ecc. (basically I didn't change the natural convection default)
The problem, as I mentioned before, is that when the simulations starts, it is a bit unstable (as it can be seen from the diagrams) and final temperatures are pretty high. I was wondering if there was a setup problem somewhat (maybe boundaries), or if there is something I'm missing.

23-01-2025-1737623802-mceclip5.jpg
23-01-2025-1737624076-mceclip8.png

I would be very grateful if someone has any suggestion or is able to help me. Thank you so much!