Instability in evaporative binary mixtures. II. The effect of Rayleigh convection

Abstract

Multi-component mixtures undergoing phase change in the presence of gravity depict instabilities whose physical origins depend upon the heating arrangement. Calculations on evaporative instability in closed systems using the example of low weight alcohols predict that cellular patterns would occur when the system is heated from above provided that the liquid depths are small compared to the vapor depths. The cellular patterns give way to long wavelength modes when the liquid depths are large because the solutal convection is dominant. When heated from below, cellular patterns can always be obtained regardless of the phase depths. Moreover, for this heating arrangement the physics shows thermal dominance at large wave numbers and solutal dominance at small wave numbers.