This Demonstration shows the behavior of three immiscible fluids subject to couette flow. The top plate is moving to the right, while the bottom plate is stationary. The velocity of each fluid is given relative to the top plate velocity. The flow is steady, incompressible, and laminar. You can vary each fluid's relative viscosity and height. The velocity distribution indicates the impact of fluid viscosity on each fluid's velocity gradient. The velocity versus height plot indicates the relative slopes (or velocity gradients) in each fluid.