Evaluate δ*/δ and θ/δ for the turbulent 1
7-power-law
velocity profile given in Problem 9.14. Compare with ratios
for the parabolic laminar boundary-layer velocity profile
given in Problem 9.10.
A fluid, with density ρ 5 1.5 slug/ft3
, flows at U 5 10 ft/s
over a flat plate 10 ft long and 3 ft wide. At the trailing edge,
the boundary-layer thickness is δ 5 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 (see Problem 9.41).