Consider the incompressible viscous flow over a flat plate. following the theme set in prob. 4.43, show analytically that (a) for fully turbulent flow, skin friction drag varies as , and (b) for fully laminar flow, skin friction drag varies as v approaches 1.5

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]