Question: For laminar flow over a constant-heat-flux surface develop two expressions for the mean Nusselt number. In the first case base the heat-transfer coefficient on the temperature difference between the average surface temperature and the ambient; in the second case let the temperature difference be the surface minus the ambient at ½L. Compare the two mean Nusselt numbers with those for a constant-wall-temperature surface, Eq., at Prandtl numbers of 0.1,0.72, 1.0, and 100.0, and discuss.
Nu = 4 Nux
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