Normal if we want to simulate the cooling of an object by forced convection, we create a mesh of air around the object and provide the air with a velocity. Imagine we have a parallel shaft with cooling fins (and so therefore it does not have a uniform diameter throughout), which undergoes forced convection. How can one model this scenario? Modeling it as a linear air flow would not be accurate.
The only idea I have is to create an air mesh in the shape of a doughnut around the shaft, with a very small slice missing and then define an air flow within the doughnut. Are there any other options (I know I could also setup a regular heat transfer simulation and chose a convection coefficient but that is only as accurate as the convection coefficients I choose, which would be a guesstimates)