Deformational instability of a plane interface with perpendicular linear and exponential concentration gradients

A linear, hydrodynamical stability analysis is carried out for the deformation of an originally plane interface between two immiscible liquid phases with perpendicular linear or exponential concentration gradients of a third component. The results are compared with observations on the ethylene glycol-ethyl acetate-acetic acid system studied by Orell and Westwater. The normal mode of maximum instability is well in accordance with the dimensions of the convection cells reported by these authors. Two critical wavelengths of perturbation are found in the case of an exponential profile, in contrast to the single critical wavelength found for a linear profile. This fact is qualitatively explained by means of an exergy release/excess dissipation principle pertinent to the appearance of hydrodynamical dissipative structures. © 1977.SCOPUS: ar.j