A circular pipe of 25-mm outside diameter is placed in an airstream at 25C and l-atm pressure.

Question:

A circular pipe of 25-mm outside diameter is placed in an airstream at 25°C and l-atm pressure. The air moves in cross flow over the pipe at 15 m/s, while the outer surface of the pipe is maintained at 100°C. What is the drag force exerted on the pipe per unit length? What is the rate of heat transfer from the pipe per unit length?