[samob917]

I am modeling a porous media combustion chamber and I would like to experiment with nonconstant porosity. I have a U-shaped porous region (there is a divider wall in a rectangular region). Right now, I have a constant porosity, but I would like the porosity to vary from the entrance to the exit of the porous media, specifically, I want a linear variation in porosity in the flow path.

I have tried to solve this problem using named expressions- I used distance from inlet but the impacted region did not go around the U-region and just went straight to the wall parallel to the inlet and stopped. I would use the coordinates but the entire body is parametrized and will be changing so set coordinates will not work. I could not find a way to parametrize the flow path specifically and I do not know if that makes physical sense since the flow path may be impacted by the porous media (correct me if Im wrong!).

Any advice would be appreciated. Thank you!