Still learning this program but currently I'm trying to simulate natural convection and thermal condution of a heatsink-like aluminium object. The thermal energy enters the object from the bottom.
If I apply film coefficients to the heat dissipating top surfaces and heat flux from the bottom, only the bottom gets heated, the rest of the object stays cold. If I don't apply the film coefficients, the object heats up properly but natural convection doesn't get calculated properly, right? I've used the free hanging method.
What am I missing here? I'd like to be able to see how air flows in natural convection between the heatsink fins, how the object distributes the heat AND how it all combines i.e. how well does the heatsink dissipate the heat from a constant heat source.
Checkout this section of the users guide on how to setup external natural convection models!
Sounds like you want to be using the chimney approach.