Chapter 5, Problem 5.25P

Air at 20oC and 1 atm flows over a flat plate at 35 m/s. The plate is 75 cm long and 100 cm depth and is maintained at 60oC. Calculate (a) velocity boundary layer thickness at the leading edge, (b) thermal boundary layer thickness at the distance of 10 cm from the leading edge, and (c) thermal boundary layer thickness at the trailing edge.

A 10-cm-diameter, 30-cm-high cylindrical bottle contains cold water at 3°C. The bottle is placed in windy air at 27°C. The water temperature is measured to be 11°C after 45 min of cooling. Disregarding radiation effects and heat transfer from the top and bottom surfaces, estimate the average wind velocity.

Airstream at 1 atm flows, with a velocity of 15 m/s, in parallel over a 3-m-long flat plate where there is an unheated starting length of 1 m. The airstream has a temperature of 20°C and the heated section of the flat plate is maintained at a constant temperature of 80°C. Determine (a) the local convection heat transfer coefficient at the trailing edge and (b) the average convection heat transfer coefficient for the heated section.