Onset of Oscillatory Convection in a Binary Fluid Mixture

Abstract

Flow-visualization experiments are described which study the onset of convection in ethanolwater mixtures. It is shown that the conducting state becomes unstable to oscillatory convection, and the onset Rayleigh number, the frequency of oscillation, the linear growth rate of the instability, and the spatial pattern of the flow are studied as functions of the parameters of the fluid mixtures. This oscillatory fluid motion does not stabilize at a finite amplitude but grows exponentially with time until large-amplitude, overturning convection is triggered.