Spontaneous Phase Separation of Ternary Fluid Mixtures

Abstract

We computationally study the spontaneous phase separation of ternary fluid mixtures using the lattice Boltzmann method, both when all the surface tensions are equal and when they have different values. Previous theoretical works typically rely on analysing the sign of the eigenvalues resulting from a simple linear stability analysis, but we find this does not explain the fluid morphologies observed. Here, by combining systematic computer simulations over the full range of the composition space and theoretical analysis on the eigenvalues and eigenvectors of the unstable modes, we identify four fundamental phase separation pathways. In particular, we highlight a dominant but so-far overlooked mechanism involving enrichment and instability of the minor component at the fluidfluid interface.