Influence of the heating rate on supercritical Rayleigh-Bénard convection

Abstract The time dynamics of Rayleigh-Benard convection originating from different heating rates for a Boussinesq fluid of Prandtl number Pr = 0.71 (air) has been studied numerically inside a three-dimensional (3D) rectangular box of aspect ratios γ z = 1.25, γ y = 2. The heating rate, introduced through a time dependent Rayleigh number R ( t ), drives a flow transition at least in the range of supercritical Rayleigh numbers ( R s ) here considered to solve the governing equations; R s = 3.6 x 10 3 , 5 × 10 3 , 9 × 10 3 , 1.3 × 10 4 and 1.6 × 10 4 . The flow transition, identified by a change of the rotation sense of a two-roll fluid pattern was found when perfectly conducting side walls were used. This kind of flow transition has been reported in recent experiments.