Transient Mixed Convection Coupled with Surface Radiation inside a Square Cavity with Different Configurations - A Critical Study

Abstract

The conjugate heat transfer within differentially heated enclosure in presence of surface radiation is a complex phenomenon, which has become a research topic because of its practical relevance. The flow and heat transfer depends on the orientation of source of buoyancy and shear force. Buoyancy driven flow depends on the terminal temperature difference between the walls and its orientation. Similarly, the shear driven flow depends on the wall movement and its direction. The interaction between the shear induced flow with the buoyancy induced flow caused due to different orientation of differential heating of walls in presence of surface radiation is studied in the present article. The governing equations of mass, momentum and energy are solved using modified MAC method. The unsteady flow and heat transfer characteristics significantly vary with the magnitude of velocity and the direction of wall movement. The relative importance of different influencing parameters such as Rayleigh number (Ra), emissivity (ε) and Richardson number (Ri) has been analyzed in the present study. It is noticed that direction of wall movement and Rayleigh number affect both steady and unsteady flow patterns and heat transport processes in the cavity. Presence of surface radiation significantly changes the flow structures in case of vertical wall movement compared to horizontal wall movement for bottom heated cavity. Period of transience for shear dominated regimes (Ri << 1) is less compared to buoyancy dominated regimes (Ri >> 1). This study finds its application in industrial convection ovens and uninterrupted-flow in bakery systems, in food processing industries.