The laminar mixed convection in a vertical annular duct is studied. The fully developed region is considered under the hypothesis of parallel flow. The momentum local-balance equation and the energy local-balance equation are solved analytically by means of the Fourier-series expansions method. Moreover, the Fanning friction factors are determined. Two particular cases are considered: an annular duct with the inner wall adiabatic and the outer wall subjected to a sinusoidal heat-flux distribution in the angular direction; an annulus with the inner wall subjected to a sinusoidal heat-flux distribution and the outer wall adiabatic. The threshold value of the ratio Gr/Re for the onset of the phenomenon of flow reversal is determined as a function of the duct aspect ratio. Finally, the solution for a more general case is determined: the annular duct has both walls subjected to arbitrary heat-flux distributions, which can be described as Fourier sine series with respect to the angular coordinate.
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|Titolo:||Convection in a vertical annular duct with circumferentially variable boundary conditions|
|Data di pubblicazione:||2004|
|Appare nelle tipologie:||01.01 - Articolo su rivista|