Issue 2, 2021

Alignment and scattering of colliding active droplets

Abstract

Active droplets emit a chemical solute at their surface that modifies their local interfacial tension. They exploit the nonlinear coupling of the convective transport of solute to the resulting Marangoni flows in order to self-propel. Such swimming droplets are by nature anti-chemotactic and are repelled by their own chemical wake or their neighbours. The rebound dynamics resulting from pairwise droplet interactions was recently analysed in detail for purely head-on collisions using a specific bispherical approach. Here, we extend this analysis and propose a reduced model of a generic collision to characterise the alignment and scattering properties of oblique droplet collisions and their potential impact on collective droplet dynamics. A systematic alignment of the droplets’ trajectories is observed for symmetric collisions, when the droplets interact directly, and arises from the finite-time rearrangement of the droplets’ chemical wake during the collision. For more generic collisions, complex and diverse dynamical regimes are observed, whether the droplets interact directly or through their chemical wake, resulting in a significant scattering.

Graphical abstract: Alignment and scattering of colliding active droplets

Article information

Article type
Paper
Submitted
13 Jul 2020
Accepted
01 Oct 2020
First published
10 Nov 2020
This article is Open Access
Creative Commons BY-NC license

Soft Matter, 2021,17, 365-375

Alignment and scattering of colliding active droplets

K. Lippera, M. Benzaquen and S. Michelin, Soft Matter, 2021, 17, 365 DOI: 10.1039/D0SM01285H

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