[jjnud]

Hello, I'm very new to FloEFD/CFD, and am having trouble finding some information online relevant to what I'm looking for.

I'm designing an aluminum enclosure that houses 2 boards, each with a chip that generates 9W of heat, a heat sink on each chip, a power source that generates 24W of heat, and polystyrene insulation. I've defined the materials, the heat sources, and the goals as max temp of the chip and convective heat transfer rate from the heat sink.

Below is a picture of the design. My question deals with how to handle the boundary conditions. I've defined ambient temp outside the enclosure to be 40 C, and the exterior walls to have a convective coefficient of 10 W/m^2/K. However, I also need the simulation to account for convection inside the box. If I set up boundary conditions inside the box so that all surfaces (chips, heat sinks, pcb's, and insulation) are real walls, and there is a convective coefficient of 5 W/m^2/k, I also need to define the temperature inside the box, which I don't know, and rather wouldn't assume.

Is there any way to leave the fluid temperature inside the box undefined, but still account for convection inside the box? Any other suggestions, or relevant resources online for simulating heat transfer inside an enclosure? By the way, I have it set to external flow, while including internal components. I believe that's the correct configuration.

Thanks in advance!