A number of different types of flow chambers have

been designed to study adhesion between cells in vitro.

One important design feature is the ability to have a

range of shear stresses. This ability allows a wide range

of data to be collected in a single experiment, reducing

experimental variability. In one such device, called a

radial flow channel, the fluid flows outward from a

source of radius $R$ in the radial direction between two

parallel discs of radius $R,$ distance $2$B apart, under a pressure drop of $(P_R-P_R).$ Assuming that the Reynold's number is much less than unity $($creeping flow$),$ determine the velocity profile for this flow.