Influence of geometric parameters on flow and temperature characteristics in partitioned thermal convection

Abstract

An unprecedented heat-transport enhancement of the Rayleigh-Benard convection can be leaded by inserting vertical partitions with thin gaps left open between the partition walls and cooling/heating plates. The more geometric parameters appeared in the partitioned thermal convection. The two-dimensional direct numerical simulations (DNS) were performed for partitioned thermal convection with the various aspect ratio Γ , height of gap d and width of channel b , and the influence of geometric parameters on the flow characteristics is discussed. The flow characteristics are mainly reflected by the average velocity of the gaps and the average velocity of the channels, and the temperature distribution is mainly reflected by TD number that characterizing the magnitude of temperature in the channels. The results show that flow characteristics and temperature distribution of different systems are basically the same when the local height of gap d and width of channel b are the same, and the aspect ratio of the whole system has little effect. By analyzing a great deal of results of numerical simulation, we can estimate that d is the critical geometric parameter that controls the flow and temperature characteristics in the case of b ≥4 d at Ra =108 and Pr =5.3 for the different height of gap d and width of channel b . In addition, the flow in the gaps is two-dimensional Poiseuille flow, and it decouples from the temperature distribution but has function as a transporter of the horizontal heat flow. The height of gap d has little influence on the velocity in the gaps, but affects the flow and temperature characteristics of the whole system.