A 2-D suspension of active agents: the role of fluid mediated interactions

TL;DR

This paper investigates how fluid-mediated long-range hydrodynamic interactions influence the collective ordering and clustering behavior of active agents in a quasi-2D suspension, considering both short-range and long-range effects.

Contribution

It introduces a combined analysis of Vicsek-like short-range interactions and far-field hydrodynamics in a 2D active suspension, highlighting their impact on ordering phenomena.

Findings

Hydrodynamic interactions enhance clustering at high densities.

Long-range interactions influence velocity correlations and number fluctuations.

Clustering behavior depends on particle density and noise strength.

Abstract

Taking into account simultaneously the Vicsek short range ordering and also the far-field hydrodynamic interactions mediated by the ambient fluid, we investigate the role of long range interactions in the ordering phenomena in a quasi 2-dimensional active suspension. By studying the number fluctuations, the velocity correlation functions and cluster size distribution function, we observe that depending on the number density of swimmers and the strength of noise, the hydrodynamic interactions affect the ordering in a suspension. For a fixed value of noise, at large density of particles, long range interactions enhance the clustering in the system.