BINARY-FLUID CONVECTION IN A CYLINDER

The onset of convection in binary fluid mixtures in a vertical cylinder is considered. Parameter values and boundary conditions relevant to experiments on -43He and water-ethanol mixtures with negative separation ratio are used. The azimuthal wave number of the first unstable mode is calculated as a function of the separation ratio, as are the critical Rayleigh numbers and oscillation frequencies. The eigenfunctions take the form of left-handed or right-handed rigidly rotating spirals. Depending on the azimuthal wave number, the spirals may be spatially extended, filling the container, or confined to its boundary. The results are compared with ongoing experiments. © 1995 The American Physical Society.