Air enters a square duct through a 1-ft opening as shown in Fig. P9.15. Because the boun...

Air enters a square duct through a 1-ft opening as shown in Fig. P9.15. Because the boundary layer displacement thickness increases in the direction of flow, it is necessary to increase the cross-sectional size of the duct if a constant U = 2 ft/s velocity is to be maintained outside the boundary layer. Plot a graph of the duct size, d, as a function of x for 0 ≤ x ≤ 10 ft if U is to remain constant. Assume laminar flow.