Porous media with cfd

I'm trying to join three consecutive tubes, the first with turbulent flow,
the second with a porous medium, and the last turbulent again.

I'd like to solve all the parameters continuously, in particular the speed and pressure.
I should put the same name of parameters in both physicals ( u,v,w,p), but the speed is still not continuous.
That is, at the end of the first tube velocity falls to zero, the second starts at zero and so forth.

Does anybody know which is the better way to solve this problem?