Trying to setup a pressure drop simulation
 

Well I am trying to setup a pressure drop within my system in such a way to find the mass flow rate in and out. I want a pressure drop of -10kPa while using the viscosity limits of non-Newtonian power law. I have it setup as pressure-inlet of 0kPa and pressure-outlet of -10kPa, though when I simulate this problem the mass flow rate in doesn't equal the mass flow rate out :confused:

Can anyone shed some light on how to make a constraint to make mfi=mfo