Immersed Boundary Simulations of Active Fluid Droplets

TL;DR

This paper introduces 2D immersed boundary simulations of active fluid droplets, revealing complex behaviors like symmetry breaking and cell-like dynamics, useful for understanding active matter and confinement effects.

Contribution

The work develops a numerical immersed boundary method for simulating active fluid droplets with novel active interface and internal active polar fluid models.

Findings

Demonstrates spontaneous symmetry breaking and steady state dynamics

Reveals behaviors resembling cell motility and division

Shows complex feedback mechanisms with minimal degrees of freedom

Abstract

We present numerical simulations of active fluid droplets immersed in an external fluid in 2-dimensions { using} an Immersed Boundary method to simulate the fluid droplet interface as a Lagrangian mesh. We present results from two example systems, firstly an active isotropic fluid boundary consisting of particles that can bind and unbind from the interface and generate surface tension gradients through active contractility. Secondly, a droplet filled with an active polar fluid with { homeotropic} anchoring at the droplet interface. These two systems demonstrate spontaneous symmetry breaking and steady state dynamics resembling cell motility and division and show complex feedback mechanisms with minimal degrees of freedom. The simulations outlined here will be useful for quantifying the wide range of dynamics observable in these active systems and modelling the effects of confinement in a consistent and adaptable way.