Buckled in translation

TL;DR

This paper investigates how elastic fibers deform and move in a viscous cellular flow, revealing buckling behavior near stagnation points and how flexibility influences transport efficiency.

Contribution

It introduces experimental analysis of fiber buckling in cellular flows and quantifies the influence of elastic and viscous forces on this instability.

Findings

Buckling occurs near stagnation points when viscous and elastic forces balance.

Flexible fibers escape vortices faster than rigid ones.

Deformation alters fiber transport properties in the flow.

Abstract

We report experiments on the deformation and transport of an elastic fiber in a viscous cellular flow, namely a lattice of counter-rotative vortices. We show that the fiber can buckle when approaching a stagnation point. By tuning either the flow or fiber properties, we measure the onset of this buckling instability. The buckling threshold is determined by the relative intensity of viscous and elastic forces, the elasto-viscous number Sp. Moreover we show that flexible fibers escape faster from a vortex (formed by closed streamlines) compared to rigid fibers. As a consequence, the deformation of the fiber changes its transport properties in the cellular flow.