Hydrodynamics of self-propelled hard rods

TL;DR

This paper develops a continuum hydrodynamic model for self-propelled hard rods on a substrate, analyzing their collective behavior, steady states, and stability based on particle density and propulsion speed.

Contribution

It introduces a novel continuum framework for self-propelled rods with finite size and non-thermal noise, linking microscopic dynamics to macroscopic steady states.

Findings

Identification of different steady states depending on packing fraction and propulsion speed

Analysis of stability criteria for collective motion

Derivation of hydrodynamic equations from microscopic models

Abstract

Motivated by recent simulations and by experiments on aggregation of gliding bacteria, we study a model of the collective dynamics of self-propelled hard rods on a substrate in two dimensions. The rods have finite size, interact via excluded volume and their dynamics is overdamped by the interaction with the substrate. Starting from a microscopic model with non-thermal noise sources, a continuum description of the system is derived. The hydrodynamic equations are then used to characterize the possible steady states of the systems and their stability as a function of the particles packing fraction and the speed of self propulsion.