Chapter 9, Problem 13P

A fluid, with density ρ = 1.5 slug/ft³, flows at U = 10 ft/s over a flat plate 10 ft long and 3 ft wide. At the trailing edge, the boundary-layer thickness is δ = 1 in. Assume the velocity profile is linear, as shown, and that the flow is two-dimensional (flow conditions are independent of z). Using control volume abcd, shown by the dashed lines, compute the mass flow rate across surface ab. Determine the drag force on the upper surface of the plate. Explain how this viscous drag can be computed from the given data even though we do not know the fluid viscosity.