Unidirectional Porous Media applied to curved sufaces?

Dear Flow Simulation Experts,

I would like to apply an unidirectional porous media to a curvedheat exchanger. In theory, the unidirectional is appropriatedbecause I have offset strip fins.
Can I do it?

The problem with unidirectional is that the main direction (X, Y, Zof Global Coordinate System) is not aligned to the flow pathbecause it goes around a half circle. I tried to create an newcoordinate system but it does not appear as an option to porousmedia editor.

thanks,SolidworksFlow Simulation