The mechanics of disclination emergence in 3D active nematics

TL;DR

This paper investigates the mechanics of disclination formation in 3D active nematics through large-scale simulations, revealing a key parameter governing behavior and developing a visualization method and unified theory applicable to various liquid crystal systems.

Contribution

It introduces a comprehensive simulation-based analysis of disclination mechanics in 3D active nematics, including a new visualization approach and a unified theoretical framework.

Findings

Disclination emergence is governed by an activity-dependent effective stiffness.

A new visualization method for director fields during disclination formation.

A unified theory for disclination mechanics across bend and twist regimes.

Abstract

The spontaneous creation of disclinations is a defining characteristic of active nematics, which is rarely observed in equilibrium systems or other active matter systems. Thus, understanding the mechanics of disclinations is crucial for developing reliable continuum theories and practical applications. In this work, we explore this intrinsic mechanics by performing large-scale 3D simulations of a particle-based model of active semiflexible filaments. We investigate the effects of filament stiffness and activity on the collective behavior of active nematics. Analysis of the steady state and the topological properties of initial disclination loops reveals that the system is governed by a single parameter, an activity-dependent effective stiffness. Then, we develop a method to visualize director field orientations in a physically transparent manner during the formation of disclination loops. Based on this, we establish a unified theory for the mechanics of disclination emergence, across the range of bend and twist. This disclination analysis framework can also be applied to diverse other 3D liquid crystal systems.