Elastohydrodynamics of 3D chemically active filaments

TL;DR

This paper explores the complex three-dimensional behaviors of chemically active, deformable filaments in viscous flow, revealing how increasing activity or decreasing stiffness leads to buckling and diverse dynamic states.

Contribution

It combines phoretic theory with elastohydrodynamic modeling to analyze the nonlinear dynamics of chemically propelled filaments beyond buckling thresholds.

Findings

Filaments undergo buckling instabilities with increased activity or decreased stiffness.

Decreased filament stiffness leads to transitions from rigid motion to buckling and diffusive behaviors.

The study provides a framework for understanding chemoelastohydrodynamics of active filaments.

Abstract

Active deformable filaments exhibit a large range of qualitatively different three-dimensional dynamics, depending on their flexibility, the strength and nature of the active forcing, and the surrounding environment. We investigate the dynamic behaviour of elastic, chemically propelled phoretic filaments, combining two existing models; a local version of slender phoretic theory, which determines the resulting slip flows for chemically propelled filaments with a given shape and chemical patterning, is paired with a computationally efficient method for capturing the elastohydrodynamics of a deformable filament in viscous flow to study the chemoelastohydrodynamics of filaments. As the activity increases, or equivalently the filament stiffness decreases, these filaments undergo buckling instabilities that alter their behaviour from rigid rods. We follow their behaviour well beyond the buckling threshold to find a rich array of dynamics. Through two illustrative examples, we conduct initial-value simulations that show that, as the stiffness of the filament is decreased, the dynamic behaviour moves from rigid motion to planar buckling, through an out-of-plane transition, eventually reaching diffusive-like behaviours for very deformable filaments.