Tumbling of asymmetric microrods in a microchannel flow

TL;DR

This study investigates how asymmetric microrods in microchannel flow exhibit complex tumbling behaviors, confirming theoretical predictions about shape sensitivity and initial orientation effects on their orientational dynamics.

Contribution

The paper provides experimental validation of theoretical models by measuring the orientational motion of asymmetric microrods and highlighting the influence of particle shape and initial orientation.

Findings

Orientational dynamics depend strongly on particle shape.

Particles with slight asymmetry do not exhibit periodic tumbling.

Experimental results confirm theoretical predictions about shape sensitivity.

Abstract

We describe results of measurements of the orientational motion of glass microrods in a microchannel flow, following the orientational motion of particles with different shapes. We determine how the orientational dynamics depends on the shape of the particle and on its initial orientation. We find that the dynamics depends so sensitively on the degree to which particle axisymmetry is broken that it is difficult to find particles that are sufficiently axisymmetric so that they exhibit periodic tumbling ("Jeffery orbits"). The results of our measurements confirm earlier theoretical analysis predicting sensitive dependence on particle shape and its initial orientation. Our results illustrate the different types of orientational dynamics for asymmetric particles predicted by theory.