Destabilization and phase separation of particle suspensions in emulsions

TL;DR

This study investigates how particles in emulsions affect sedimentation and phase separation, revealing complex behaviors not predicted by classical models, supported by experiments and a new mathematical model.

Contribution

The paper introduces a minimal mathematical model for emulsion drainage with particles, explaining experimental observations of phase separation and sedimentation.

Findings

Particle sedimentation is enhanced by emulsion drainage.

Emulsion drainage can be arrested or accelerated by particle content.

The model accurately predicts stability and sedimentation dynamics.

Abstract

Yield stress fluids are widely used in industrial application to arrest dense solid particles, which can be studied by using a concentrated emulsion as a model fluid. We show in experiments that particle sedimentation in emulsions cannot be predicted by the classical criterion for spheres embedded in a yield stress fluid. Phase separation processes take place, where a liquid layer forms and particle sedimentation is enhanced by the emulsion drainage. In addition, emulsion drainage can be arrested or enhanced by the amount of particles embedded in the emulsion. A minimal mathematical model is developed and solved in numerical simulations to describe the emulsion drainage in the presence of particles, which favorably compares with the experimental stability diagram and the sedimentation dynamics.