Annular flow with inner cylinder moving axially (see Fig. 2B.7). A cylindrical rod of diame- ter KR moves axially with velocity vo along the axis of a cylindrical cavity of radius R as seer in the figure. The pressure at both ends of the cavity is the same, so that the fluid moves through the annular region solely because of the rod motion. Fluid at modified pressure Po Rod of radius кR' moving with velocity vo Cylinder of inside radius R Fluid at modified pressure Po Fig. 2B.7 Annular flow with the inner cylinder moving axially. (a) Find the velocity distribution in the narrow annular region. (b) Find the mass rate of flow through the annular region. (c) Obtain the viscous force acting on the rod over the length L.