Spontaneous stable rotation of flocking flexible active matter

TL;DR

This paper models flocking flexible active matter to explain spontaneous stable cluster rotation, revealing dependencies on flexibility, node count, and active force, aligning with natural observations of animals like worms and dogs.

Contribution

Introduces an $n$-node flexible active matter model that explains spontaneous stable rotation in flocking systems, highlighting the role of body alignment and active forces.

Findings

Angular velocity linearly related to chirality with a factor of 1.86

Rotation speed depends on flexibility, node number, and active force

Model explains observed stable rotations in natural flocking animals

Abstract

In nature, active matter, such as worms or dogs, tend to spontaneously form a stable rotational cluster when they flock to the same food source on an unregulated and unconfined surface. {In this paper we present an $n$-node flexible active matter model to study the collective motion due to the flocking of individual agents on a two-dimensional surface, and confirm that there exists a spontaneous stable cluster rotation synchronizing with a chirality produced by the alignment of their bodies under the impetus of the active force.} A prefactor of 1.86 is obtained for the linear relationship between normalized angular velocity and chirality. The angular velocity of such a rotation is found to be dependent on the individual flexibility, the number of nodes in each individual, and the magnitude of the active force. The conclusions well explain the spontaneous stable rotation of clusters that exists in many flexible active matter, like worms or {dogs}, when they flock to the same single source.