5.20 The flow between stationary parallel plates separated by distance 2b is driven by a pressure gradient. The velocity field is given by u=U 1−

y b

2

, where U is the centerline velocity and y is measured from the centerline. Evaluate the rates of linear and angular deformation. Obtain an expression for the vorticity vector,

ζ, and find the location where the vorticity is a maximum.