The deformation of a flexible fiber settling in a quiescent viscous fluid

TL;DR

This study investigates how flexible fibers settle in viscous fluids, revealing three distinct deformation regimes with different drag behaviors through experiments, simulations, and scaling analysis.

Contribution

It introduces a comprehensive analysis of the equilibrium configurations and deformation regimes of flexible fibers in viscous fluids, combining experimental, numerical, and theoretical approaches.

Findings

Identification of three deformation regimes

Drag proportionality varies with deformation regime

Intermediate elastic reconfiguration reduces drag

Abstract

The equilibrium state of a flexible fiber settling in a viscous fluid is examined using a combination of macroscopic experiments, numerical simulations and scaling arguments. We identify three regimes having different signatures on this equilibrium configuration of the elastic filament: weak and large deformation regimes wherein the drag is proportional to the settling velocity as expected in Stokes flow and an intermediate elastic reconfiguration regime where the filament deforms to adopt a shape with a smaller drag which is no longer linearly proportional to the velocity.