Marangoni instabilities in liquid mixtures with Soret effects

The stability of a binary liquid mixture heated from above is analysed. The heat transfer is driven by the imposed temperature difference between the horizontal bottom plate and the ambient gas. The mass flux in the layer is induced by the Soret effect. The gravitational effects are ignored, and the instability is driven by solutocapillarity and retarded by thermocapillarity. The interface is allowed to deform, and both the small-wavenumber and the Pearson-type instabilities are studied. Oscillatory instability can exist when the thermocapillary is destabilizing and the solutocapillarity is stabilizing.