Buoyancy-induced recirculation bubbles and heat convection of developing flow in vertical channels with fin arrays

Abstract

Developing fluid flow and heat transfer characteristics of the mixed convection in a vertical parallel-plate channel with fin array are analyzed in this study. The channel walls are maintained at uniform but unequal temperatures, and the fins of extremely high thermal conductivity are mounted on the relatively hotter wall. The stream function-vorticity method coupled with the power-law scheme are employed to solve the continuity, momentum and energy equations numerically. Results show that the streamwise periodic variation of the cross-sectional area causes the flow and temperature fields to attain a periodically fully developed character after a number of modules from the inlet. Meanwhile, if wall heating is sufficiently strong, an adverse pressure gradient can be developed downstream in the channel, and a series of buoyancy-induced recirculation bubbles may appear adjacent to the colder wall. The periodically fully developed solutions provided by Cheng et al. ( Int. J. Heat Mass Transfer 1992, 35, 2643–2653) are found to accurately portray the behavior of the present developing flow in the downstream region.