The separation of plumes from a horizontal fin attached to a sidewall of a differentially heated cavity is numerically studied over a range of Rayleigh numbers and fin heights. The simulation results reveal that the plume separation frequency increases with the Rayleigh number and decreases with the fin height. The decrease of the separation frequency with the fin height is mainly due to the cavity scale temperature stratification. It is demonstrated that the temperature difference in the unstable layer above the fin decreases with increasing fin height. Both the local Reynolds number and Rayleigh number in the unstable layer are non-monotonic functions of the fin height due to the complex flow patterns in the cavity caused by the fin. It is also found that the heat transfer rate through the heated sidewall is significantly enhanced due to temperature oscillations induced by the separating plumes. An optimum fin height for heat transfer enhancement has been identified for Rayleigh numbers greater than 1.84×10~9.
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