Experiments to determine the local convection heat transfer coefficient for uniform flow normal to a heated circular disk have yielded a radial Nusselt number distribution of the form where both n are a are positive. The Nusselt number at the stagnation point is correlated in terms of the Reynolds (ReD = VD/v) and Prandtl numbers Obtain an expression for the average Nusselt number.

NuD = hD/k, corresponding to heat transfer from an isothermal disk. Typically, boundary layer development from a stagnation point yields a decaying convection coefficient with increasing distance from the stagnation point. Provide a plausible explanation for why the opposite trend is observed for the disk.

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h(r)D Nu, Nip r=UJU 0.814Re PAM Nu, =