For CHT (Conjugate Heat Transfer) simulations the requirements for the flow region are slightly different from the normal procedure where we create a flow volume covering the negative of our overflowed geometry which represents the physical walls. This article describes how to proceed for CHT simulations.
A) Create Flow Volume and Keep Existing Parts
In CHT simulations we need to keep the original solid parts as they participate in the heat transfer. Accordingly, when we create the flow volume we need to keep the existing parts.
As an example, the following image shows the case of an electronics box:
In order to understand the difference, the following picture shows both the results for a flow volume with and without keeping the existing parts:
This is only necessary if you have a CHT simulation (or when you want to see the heat transfer through the walls / solids). In any other simulation you will get the same results, whether you keep the existing parts or not.
B) Imprint the Geometry
In order to know where the physical contacts between two solids are, we need to perform an imprint. This action basically cuts surfaces describing physical contact. This article describes what an imprint does more specifically.
As a result, when we create the CHT simulation, the tool detects the interfaces automatically. If you need to, you can further change the thermal properties of the interfaces.