Oscillatory Binary Fluid Convection in Finite Containers

Linear and weakly nonlinear theory of overstable convection in large but bounded containers is reviewed and the results compared with detailed numerical simulations of binary fluid convection in a two-dimensional domain with realistic boundary conditions. For sufficiently negative separation ratios convection sets in as growing oscillations; the corresponding eigenfunctions take the form of ‘chevrons’ of either odd or even parity. These may bifurcate sub- or supercritically. Simulations of 3He—4He and water-ethanol mixtures show that the oscillations may equilibrate in finite amplitude chevron states, or that these states are unstable to blinking or repeated transient states. The results compare favorably with available experiments.