Hi peteroznewman,

Yes, the heat transfer I am interested in are in all directions (x, y, z).

In Ansys Discovery, the modle looks like this:

Different colors represent different material, which means different thermal conductivity. Except the yellow and the red part are the same material but the red part does self heat generation.

I am not sure what you meant by 'BC'.

All different mateirals (lays) are contact tightly to each other. I am doing steady state themal simulation with Ansys Mechanical, which I believe is using Finite Element method to solve the problem. Therefore, thermal resistance is not typically involved. So I am not very sure what you meant. Will really appreciate if you could explain with more details. Also please correct me if I am wrong. I thought thermal resistance is used while the thermal model is approached through a way using thermal RC netowork.