Oscillations of confined fibers transported in microchannels

TL;DR

This study explores how rigid fibers move in microchannels under low Reynolds number flow, revealing complex oscillatory trajectories influenced by confinement, with experimental and simulation analysis providing a comprehensive understanding.

Contribution

It introduces a detailed analysis of fiber oscillations in confined microfluidic flows, combining experiments and simulations to characterize their complex trajectories.

Findings

Fibers exhibit oscillatory motion influenced by confinement.

A complete state diagram of fiber behaviors is developed.

Viscous friction and wall effects are key factors in trajectory complexity.

Abstract

We investigate the trajectories of rigid fibers as they are transported in a pressure-driven flow, at low Reynolds number, in shallow Hele Shaw cells. The transverse confinement and the resulting viscous friction on these elongated objects, as well as the lateral confinement (i.e. the presence of lateral walls), lead to complex fibers trajectories that we characterize with a combination of microfluidic experiments and simulations using modified Brinkman equations. We show that the transported fiber behaves as an oscillator for which we obtain and analyze a complete state diagram.