Vortex formation in the Vicsek model with internal chirality of self-propelling objects

TL;DR

This study investigates how internal chirality affects collective motion in a modified Vicsek model, revealing vortex formation and changes in movement behavior due to chirality-induced asymmetry.

Contribution

It introduces a modified Vicsek model with fixed angular noise to explore the impact of internal chirality on collective dynamics and vortex formation.

Findings

Vortexes form for specific chirality ratios.

Traveling bands are destroyed at certain chirality levels.

Velocity autocorrelation indicates equilibrium in vortex states.

Abstract

Effect of internal chirality on collective motion of a large number of active objects is studied by simulations of appropriately modified Vicsek model. We add a fixed angle to the noise and consider small ratios, $p$, between this angle and the maximal deviation from the average local direction of motion. When the above ratio is $p=1/120$, the traveling bands observed with the symmetrical noise are destroyed, and small bands moving in different directions appear. Circular rotating flocks of objects with the same orientation are formed for $p=1/7.5$. Stable vortexes in the stationary state were found from $p=1/60$ to $p=1/20$. Velocity autocorrelation function shows equilibrium between the inflow and the outflow to and from the vortex. Long-time evolution is considerably influenced by a temporary trapping of the objects in the vortex. The ballistic behavior for the symmetrical noise changes to the diffusive behavior for the chirality leading to the onset of vortexes.