An important aspect of the Couette flow is that the velocity gradient and shear stress are constant throughout the flow domain provided no slip at the walls. The absence of wall slip is one of the assumptions made concerning fluid flow in the Couette Cell. The other assumptions are laminar flow and incompressible Newtonian fluid implying constant viscosity. It can also be assumed that the concentric cylinder device can be approximated by two infinite bending parallel plates. On these assumptions, the velocity gradient and the shear stress across the Couette Cell are constant. Since the shear stress is constant, the processed material experiences the same conditions everywhere except near the top and the bottom of the Couette Cell.