Consider incompressible viscous flow between two very long plates, separated by a distance h. The bottom plate is stationary, while the top plate moves at a velocity of V. The flow is subjected to a constant pressure gradient dp/dx.
Show that reversed flow (u < 0) will occur near the lower flat plate, whenever the parameter {h2/(2mV)} dp/dx is greater than unity.
Solve for u as a function of y, as done in the class for Couette flow. Determine when the velocity slope du/dy becomes negative at the lower plate.