A typical freeway billboard is 2.28 m high and 13.23 m long. Consider the case where standard air at 20◦C blows parallel to the billboard at a speed of 36 km/h. (a) Show that the boundary layer on the...

A typical freeway billboard is 2.28 m high and 13.23 m long. Consider the case where standard air at 20◦C blows parallel to the billboard at a speed of 36 km/h. (a) Show that the boundary layer on the downwind edge of the billboard is turbulent. (b) Assuming that the flow in the boundary layer is smooth turbulent over the entire billboard, estimate the boundary-layer thickness on the downwind edge of the billboard, assuming a one-seventh power law velocity distribution. (c) Estimate the boundary layer thickness on the downwind edge using the empirical formulation based partially on the one-seventh power law velocity distribution and partially on data from pipe flow. (d) Assess the statement that the formulations used in parts (b) and (c) usually give results in close agreement.