Nonquenched rotators ease flocking and memorise it

TL;DR

This paper presents a minimal model of a 2D polar flock with nonquenched rotators that enhances the robustness of flocking order and allows for better information propagation and flock monitoring.

Contribution

It introduces a hydrodynamic framework for the model and demonstrates how nonquenched heterogeneities increase sound speeds and order stability.

Findings

Nonquenched rotators improve flocking robustness.

Rotators increase sound speeds and information convection.

The model offers insights into controlling large crowds.

Abstract

We introduce a minimal model for a two-dimensional polar flock with nonquenched rotators, and show that the rotators make the usual macroscopic long-range order of the flock more robust than the clean system. The rotators memorise the flock-information which helps in establishing the robustness. Moreover, the memory of the rotators assists in probing the moving flock. We also formulate a hydrodynamic framework for the microscopic model that makes our study comprehensive. Using linearised hydrodynamics, it is shown that the presence of such nonquenched heterogeneities increases the sound speeds of the flock. The enhanced sound speeds lead to faster convection of information and consequently the robust ordering in the system. We argue that similar nonquenched heterogeneities may be useful in monitoring and controlling large crowds.