Recently I need to simplify some elements in an circulating oven. There is more than one porous media so I have to be careful on the mass flow passing through each elements.

They are radiator actually so the mass flow of each is very important to help me identify the actual individual heat power.

So I do a simple laminar tunnel test to model my porous media. What shock me is that the porous media inlet and outlet face give inconsitent mass flow rate.

Isn't it weird?