1. Simplify the appropriate Navier-Stokes equation for the ?ow between parallel plates assuming u ¼ u(y) and gravity in the z-direction. The streamlines are assumed to be parallel to the plates so that v ¼ w ¼ 0.
2. Simplify the Navier-Stokes equation for ?ow in a pipe assuming vz ¼ vzðrÞ and gravity in the z-direction. The streamlines are assumed to be parallel to the pipe wall so that vy ¼ vr ¼ 0: