On the mechanism of instability in a two-layer system with limited solubility of components

Abstract

A two-layer system of miscible liquids is a common model system in studies of both fundamental and applied problems in hydrodynamics that associated with stratified media. Rayleigh-Taylor instabilities or double diffusive one can lead to a disturbance in mechanical equilibrium if both or at least one of the components dissolved in each of the layers are initially unstable stratified. The situation when both components have a stable initial density distribution is believed that absolutely stable and, usually, is not considered by researchers. This paper experimentally demonstrates the possibility of developing instability in such systems and proposes a physical mechanism based on the dependence of the solubility of one of the components on the concentration of the second component. It is shown that the evolution of the density profile, the possibility of the development of instability, and the properties of the arising convective motion are determined by the initial position of the system on the parameters plane of the solubility diagram.