porous medium model, help please!
 

I used the method Deriving the Porous Coefficients Based on Experimental Pressure and Velocity Data in the tutorial for the porous medium model. Suppose the BCs for the detailed model and porous model at the same: Constant pressure at the inlet and 0 gauge pressure at the outlet. Then two models should give the same or close mass flow rate. But my porous medium model yelds much less mass flow rate. What happened to the porous medium model?

Thanks,
Eric