Question: 1. Consider laminar flow in a circular tube with a fully developed velocity profile. Let the tube surface be alternately heated at a constant rate per unit of length and adiabatic, with each change taking place after intervals of x+ of 0.020. How large must x+ be for the effects of the original entry length to damp out? How does the Nestlet number vary along the heated segments after the effects of the original entry length have damped out?
2. Consider the problem posed. Let β = 6 and let the tube be circular. Evaluate and plot the local Nusselt number as a function of x/L. Explain physically the reasons for the behavior noted.