Shear dynamics of polydisperse double emulsions

TL;DR

This study uses numerical simulations to explore how polydispersity and shear flow influence the behavior, interactions, and shape deformations of double emulsions, revealing complex dynamics dependent on these factors.

Contribution

It provides new insights into the shear-induced dynamics of polydisperse double emulsions, highlighting the roles of dispersity and shear rate in their behavior.

Findings

Inner drops rotate periodically at low/moderate shear rates

Higher polydispersity leads to alignment and motionlessness of drops

Increased polydispersity promotes close contacts and collisions

Abstract

We numerically study the dynamics of a polydisperse double emulsion under a symmetric shear flow. We show that both dispersity and shear rate crucially affect the behavior of the innermost drops and of the surrounding shell. While at low/moderate values of shear rates the inner drops rotate periodically around a common center of mass triggered by the fluid vortex formed within the emulsion generally regardless of their polydispersity, at higher values such dynamics occurs only at increasing polydispersity, since monodisperse drops are found to align along the shear flow and become approximately motionless at late times. Our simulations also suggest that increasing polydispersity favours close-range contacts among cores and persistent collisions, while hindering shape deformations of the external droplet. A quantitative evaluation of these effects is also provided.