Orthotropic Medium

We are trying to simulate Cooling fins in Flow Simulation by using a porous medium (as suggested by our SW provider).  This is because the complexity of the cooling coil is too complex for SW to cope with.

Unfortunately we cannot get the Orthotropic medium properties right to simulate the wave fins that we have.  The fins are very thin plates that are only 1.5mm apart and have a very small wave profile all the way along.  We are giving the low resistance values

in the x & y directions and zero in the z direction to mimic the plates.  Looking at the tracer studies we have it still looks like the medium is diving the flow in to tubes rather than the 'plated' flow that we need. 

Has anyone found a way to simulated plated flow using the porous medium?

SolidworksSimulation