Partitioning effect on natural convection in a circular enclosure with an asymmetrically placed inclined plate

Abstract

This work presents a numerical investigation on steady-state laminar natural convection in a circular enclosure with an inner flat plate at Ra=106. The plate is inclined placed along the radial direction but is asymmetric about the center of enclosure, with eccentricity defined as the distance between the centers of two entities. The enclosure and plate are kept at low and high temperatures, respectively. The objective of this study is to explore the effects of two significant parameters, i.e., eccentricity (r) and inclination (α) of the plate, on the flow and heat transfer characteristics of the enclosure-plate system. The numerical simulation is performed using our in-house fourth-order finite difference code which is well validated. The effects of the two parameters are analyzed by the total heat transfer rate, temperature distribution, formation and evolution of various vortices, and distribution of local heat transfer rate for r/D=0.00(0.05)0.20 and α=0°(5°)180° where D is the enclosure diameter. Numerical results reveal that natural convection is weakened by the partitioning effect of nearly horizontal plate since fluid circulation is greatly constrained, while the effect is minor at low and high inclinations where fluid circulation is pronounced. Depending on the eccentricity and inclination, there could be at most two and three vortices in the left and right halves of the enclosure, respectively, whose formation and spatial evolution behaviors and intensity variations exhibit complex patterns, and are closely related with the heat transfer characteristics. For high eccentricity configurations, the heat transfer in the gap can be dominated by either convection or conduction depending on the gap size, the latter of which is characterized by the expected linear variation of circumferential position of maximum local heat transfer rate with the inclination.