EVOLUTION OF THE RAYLEIGH-BENARD CONVECTION IN A RECTANGULAR BOX

We report the results on the MAC numerical simulations of the Rayleigh -Benard convection for a Boussinesq fluid with the Prandtl number Pr = 6 confined in a rectangular box with the aspect ratios Gamma(x) = 3.0 and Gamma(y) = 1.5. With increase of the Rayleigh number, the initial state with two parallel steady rolls undergoes a successive series of transitions in such a way that (i) as for the time behavior: steady - -> periodic oscillations --> quasi-periodic with two fundamental frequ encies --> chaotic; and that (ii) as for the horizontal spatial symmet ry in terms of the point group notation: C-2v --> C-1h --> C-1. In par ticular, the periodic oscillations are shown to arise from the BO2 blo b instability. The results are compared with those of the experiment o n water.