Preferential sampling of helicity by isotropic helicoids

TL;DR

This paper investigates how isotropic helicoids, particles that are symmetric under rotations but not mirror reflections, move in complex flows, revealing their ability to preferentially sample different flow helicities and enabling flow structure control.

Contribution

It introduces the first theoretical and numerical analysis of isotropic helicoids' motion in complex flows, highlighting their unique sampling behavior due to translational-rotational coupling.

Findings

Heavy isotropic helicoids preferentially sample flow regions with specific helicities.

Coupling between translation and rotation influences particle trajectories.

Potential applications in microfluidics and turbulence control.

Abstract

We present a theoretical and numerical study on the motion of isotropic helicoids in complex flows. These are particles whose motion is invariant under rotations but not under mirror reflections of the particle. This is the simplest, yet unexplored, extension of the much studied case of small spherical particles. We show that heavy isotropic helicoids, due to the coupling between translational and rotational degrees of freedom, preferentially sample different helical regions in laminar or chaotic advecting flows. This opens the way to control and engineer particles able to track complex flow structures with potential applications to microfluidics and turbulence.