Here is the zero–shear viscosity and is the yield stress. You can vary these two parameters.
For a Newtonian fluid, the mass flow rate is given by the Hagen–Poiseuille equation: .
This Demonstration plots the velocity profile (blue curve) and gives the value of the corresponding mass flow rate. In addition, the velocity profile for a Newtonian fluid is plotted (red curve). The viscosity, , of the Newtonian fluid is chosen such that both fluid mass flow rates are equal. The value of the viscosity, , is also shown.