Analysis of Turbulent Free Convection in a Rectangular Rayleigh-Benard Cell

Abstract

The present study compares results of direct numerical simulations of thermal convection within a rectangular geometry with Rayleigh-Benard convection in thin fluid layers and cylindrical geometries. It is shown that boundary layer thicknesses show similar tendencies in the rectangular geometry and a thin fluid layer, but the quasi two-dimensional geometry of the container delays the onset of convection significantly. Analysis of the thermal dissipation rates indicates that there are three distinct regimes, of the small scale contribution grows rap-idly as Rayleigh number is increasing, whereas the large scale contribution remains almost constant.