Build up of yield stress fluids via chaotic emulsification

TL;DR

This study demonstrates how to create dense yield stress emulsions through large-scale stirring, revealing the microstructure and rheological properties, including droplet size distribution and finite yield stress, in highly concentrated systems.

Contribution

It introduces a method to produce dense emulsions with controlled microstructure and rheology via stirring, linking droplet dynamics to macroscopic yield stress.

Findings

Achieved volume fractions close to 80% in emulsions.

Observed droplet size distribution with -10/3 scaling.

Quantified the visco-elastic properties and confirmed finite yield stress.

Abstract

Stabilized dense emulsions display a rich phenomenology connecting microstructure and rheology. In this work we study how an emulsion with a finite yield stress can be built via large-scale stirring. By gradually increasing the volume fraction of the dispersed minority phase, under the constant action of a stirring force, we are able to achieve volume fractions close to $80\%$. Despite the fact that our system is highly concentrated and not yet turbulent we observe a droplet size distribution consistent with the $-10/3$ scaling, often associated to inertial range droplets breakup. We report that the polydispersity of droplet sizes correlates with the dynamics of the emulsion formation process. Additionally we quantify the visco-elastic properties of the dense emulsion finally obtained and we demonstrate the presence of a finite yield stress. The approach reported can pave the way to a quantitative understanding of the complex interplay between the dynamics of mesoscale constituents and the large scale flow properties yield-stress fluids.