Rayleigh-Taylor instability in binary fluids with miscibility gap

Binary fluids with miscibility gap exhibit property variation in response to a stimuli, making them useful for applications like targeted drug delivery, protein extraction, and others. We present a novel phase-field approach to track the continuous evolution of such fluid pairs from initially immiscible/partially miscible state to miscible state with a tunable miscibility framework. The model is used to investigate classical single mode Rayleigh-Taylor instability. Three qualitatively distinct growth patterns of the imposed perturbation are found based on the Atwood and Weber numbers. A secondary instability of Kelvin-Helmholtz rolls is found to be dependent on system temperature.