Three dimensional contractile droplet under confinement

TL;DR

This study numerically explores the behavior of a 3D contractile droplet, revealing diverse shapes and motility patterns influenced by activity levels and confinement, with potential implications for microswimmer research.

Contribution

It uncovers novel oscillating dynamics of contractile droplets under confinement, expanding understanding of active fluid behavior in restricted geometries.

Findings

Droplet self-propels unidirectionally in bulk at intermediate activity.

Larger activity causes a peanut-shaped droplet.

Under confinement, droplets oscillate and hit channel walls periodically.

Abstract

We numerically study the dynamics of a three-dimensional contractile fluid droplet in the bulk and under confinement. We show that varying activity leads to a variety of shapes and motile regimes whose motion is driven by an interplay between spontaneous flows and elasticity. In the bulk the droplet self-propels unidirectionally, acquiring either an almost spherical shape at intermediate activity or a peanut-like geometry for larger values. Under confinement, the droplet exhibits a previously unreported oscillating dynamics characterized by periodic hits against opposite walls of a microchannel while moving forward. These results could be of interest for the study of artificial microswimmers and their biological analogs, such as living cells.