Traveling waves and chaos in convection in binary fluid mixtures

Rayleigh-B\'enard convection is studied in alcohol-water mixtures in which the diffusion of concentration opposes convection via the Soret effect. Near onset, the convective rolls are found to move continuously as traveling waves, in contrast to the stationary roll patterns observed in homogeneous fluids. Dependent upon the temperature difference across the fluid layer (i.e., Rayleigh number), these traveling-wave states are either periodic or chaotic. At larger Rayleigh numbers, time-independent flow is observed which is the same as that expected for the homogeneous fluid mixture.