Circling particles and drafting in optical vortices

TL;DR

This paper models particles in optical vortices, revealing how hydrodynamic interactions influence their collective motion, stability of clusters, and the importance of drafting in limit cycle behavior.

Contribution

It introduces a hydrodynamic model for particles in optical vortices and analyzes their collective dynamics and stability, emphasizing the role of drafting.

Findings

Hydrodynamic interactions govern collective particle motion.

Regular clusters exhibit specific stability properties.

Drafting of doublets is crucial for limit cycle behavior.

Abstract

Particles suspended in a viscous fluid circle in optical vortices generated by holographic optical-tweezer techniques [Curtis J E and Grier D G 2003 Phys. Rev. Lett. 90 133901]. We model this system and show that hydrodynamic interactions between the circling particles determine their collective motion. We perform a linear-stability analysis to investigate the stability of regular particle clusters and illustrate the limit cycle to which the unstable modes converge. We clarify that drafting of particle doublets is essential for the understanding of the limit cycle.