BIFURCATIONS IN 2-DIMENSIONAL RAYLEIGH-BENARD CONVECTION

Two-dimensional buoyancy-driven convection in a horizontal fluid layer with stress-free boundary conditions at top and bottom and periodic b oundary conditions in the horizontal direction is investigated by mean s of numerical simulation and bifurcation-analysis techniques. As the buoyancy forces increase, the primary stationary and symmetric convect ion rolls undergo successive Hopf bifurcations, bifurcations to travel ing waves, and phase lockings. We pay attention to symmetry breaking a nd its connection with the generation of large-scale horizontal flows. Calculations of Lyapunov exponents indicate that at a Rayleigh number of 2.3 x 10(5) no temporal chaos is reached yet, but the system moves nonchaotically on a 4-torus in phase space.