The effect of velocity boundary conditions on 2D Rayleigh-Bénard turbulence

Rayleigh-Bénard (RB) convection, the flow between a cold top plate and a hot bottom plate, is commonly used to model natural convection. Experimental realizations of RB usually consist of low aspect-ratio geometries and are limited to no-slip velocity boundary conditions. This is not representative of most geo- and astrophysical systems we wish to model. In this contribution, the effect of aspect-ratio and velocity boundary conditions on a 2D RB system have been studied by varying the sidewall boundary conditions between no-slip, stress-free and periodic, and the differences in the heat transport are measured. Heat transport is found to be larger for stress-free and periodic cells than for the no-slip case. Aspect ratio plays a small role in periodic cells, as long as the aspect ratio is larger than a certain threshold. For stress-free and no-slip cells, aspect ratio plays opposing roles. Thinner cells have larger heat transport than square cells when the sidewalls are stress-free. In contrast, for cells with no-slip walls, square cells have a larger heat transport than thin cells.