Collisions and rebounds of chemically active droplets - École polytechnique Access content directly
Journal Articles Journal of Fluid Mechanics Year : 2020

Collisions and rebounds of chemically active droplets

Abstract

Active droplets swim as a result of the nonlinear advective coupling of the distribution of chemical species they consume or release with the Marangoni flows created by their non-uniform surface distribution. Most existing models focus on the self-propulsion of a single droplet in an unbounded fluid, which arises when diffusion is slow enough (i.e. beyond a critical Péclet number, Pec). Despite its experimental relevance, the coupled dynamics of multiple droplets and/or collision with a wall remains mostly unexplored. Using a novel approach based on a moving fitted bispherical grid, the fully-coupled nonlinear dynamics of the chemical solute and flow fields are solved here to charac-terise in detail the axisymmetric collision of an active droplet with a rigid wall (or with a second droplet). The dynamics is strikingly different depending on the convective-to-diffusive transport ratio , Pe: near the self-propulsion threshold (moderate Pe), the rebound dynamics are set by chemical interactions and are well captured by asymptotic analysis; in contrast, for larger Pe, a complex and nonlinear combination of hydrodynamic and chemical effects set the detailed dynamics, including a closer approach to the wall and a velocity plateau shortly after the rebound of the droplet. The rebound characteristics, i.e. minimum distance and duration, are finally fully characterised in terms of Pe.
Fichier principal
Vignette du fichier
1912.04621.pdf (5.71 Mo) Télécharger le fichier
Origin : Files produced by the author(s)
Loading...

Dates and versions

hal-02536797 , version 1 (08-04-2020)

Identifiers

Cite

Kevin Lippera, Matvey Morozov, Michael Benzaquen, Sébastien Michelin. Collisions and rebounds of chemically active droplets. Journal of Fluid Mechanics, 2020, 886, ⟨10.1017/jfm.2019.1055⟩. ⟨hal-02536797⟩
40 View
85 Download

Altmetric

Share

Gmail Facebook X LinkedIn More