OSCILLATORY INSTABILITIES IN BINARY MIXTURES FOR POSITIVE SEPARATION RATIO

Abstract

When a layer of a binary mixture with a positive Soret coefficient is heated from below, a pattern of stationary squares can be observed. When heating is increased, this planform loses stability and an alternation of squares and rolls appears in this case. Finally, when one enters in the so-called Rayleigh regime, rolls become stable. A part of this phenomenon is described by means of a heuristic model that includes the relevant physical modes of temperature and concentration in the particular case of a mixture with an infinite Prandtl number.