Laminar flow normally persists on a smooth flat plate until a critical reynolds number value is reached. however, the flow can be tripped to a turbulent state by adding roughness to the leading edge of the plate. for a particular situation, experimental results show that the local heat transfer coefficients for laminar and turbulent conditions are:
h lam ( x ) = 1.74 w / m^ 1.5 * k x^ − 0.5
h turb ( x ) = 3.98 w / m^ 1.8 * k x ^− 0.2
calculate the average heat transfer coefficients for laminar and turbulent conditions for plates of length l = 0.1 m and 1 m.