Poiseuille-Rayleigh-Bénard mixed convection flow in a channel: Heat transfer and fluid flow patterns

Abstract

In the present work, a numerical and experimental study of mixed convection of water flow in a horizontal channel subjected to a constant heat flux is presented. An experimental setup was constructed to delineate the fluid flow patterns inside the channel, while a numerical simulation was performed to study the heat transfer characteristics of the flow. This study is performed for Rayleigh and Reynolds numbers in the range of 104 ≤ Ra≤ 106 and 25≤ Re≤ 100, respectively. The present predicted results are in good agreement with the experimental ones. The longitudinal evolution rolls revealed the existence of four zones corresponding to the entry zone, establishment zone, destabilization zone, and turbulent zone. Moreover, numerical simulations showed that the Nusselt number for the mixed convection gives higher heat transfer coefficient compared to forced convection. In addition, new correlations for the Nusselt number have been developed for the first time for the establishment length, onset and established zones as a function of Rayleigh and Reynolds numbers.