Sheared phase-separating binary mixtures with surface diffusion

TL;DR

This study investigates the phase separation dynamics of binary mixtures under shear flow with surface diffusion, revealing oscillatory domain behaviors and specific growth laws for domain sizes in different directions.

Contribution

It introduces new equations for domain size evolution under shear with surface diffusion and analyzes the effects of mobility and shear rate on phase separation.

Findings

Domain sizes grow as $t^{5/4}$ and $t^{1/4}$ in flow and shear directions.

Oscillations in physical observables due to domain stretching and bursting.

Excess viscosity decreases with increasing shear rate.

Abstract

The phase-separation process of a binary mixture with order-parameter-dependent mobility under shear flow is numerically studied. The ordering is characterized by an alternate stretching and bursting of domains which produce oscillations in the physical observables. The amplitude of such modulations reduce in time when the mobility vanishes in the bulk phase, disfavoring the growth of bubbles coming from bursted domains. We propose two equations for the typical sizes $R_x$ and $R_y$ of domains finding the long-time behaviors $R_x \sim t^{5/4}$ and $R_y \sim t^{1/4}$ in the flow and shear directions, respectively, in the case of surface diffusion. A reduction of the excess viscosity with increasing shear rate is observed in simulations.