Phase field analysis of binary mixtures with partially miscible components

Understanding the flow dynamics of two-phase systems with partially-miscible components is of great importance to the extraction and purification of chemicals. Based on the generalized bracket approach of nonequilibrium thermodynamics, we propose a phase-field model to describe binary systems with different degrees of miscibility. By formulating the concentration equation associated with one of the two components in terms of the corresponding phase velocity, we can avoid excessive numerical diffusion as the diffusive components are all hidden in the advective part of this equation. We validate our numerical strategy by solving the rising bubble problem and comparing our results with benchmark data from the literature. Further, we successfully validate the implementation of our new phase-field model under real flow conditions, i.e., with experimental observations made inside a Y-shaped microchannel. We accurately predict the position of the interface and reproduce the mixing behavior of miscible and partially miscible components. In the future, we will extend our investigation to ternary systems. © 2021