Flow around topological defects in active nematic films

Abstract

We study the active flow around isolated defects and the self-propulsion velocity of $+1/2$ defects in an active nematic film with both viscous dissipation (with viscosity $\eta$) and frictional damping $\Gamma$ with a substrate. The interplay between these two dissipation mechanisms is controlled by the hydrodynamic dissipation length ${\ell }_d=\sqrt{\eta /\Gamma }$ that screens the flows. For an isolated defect, in the absence of screening from other defects, the size of the vortical flows around the defect is controlled by the system size $R$. In the presence of friction that leads to a finite value of ${\ell }_d$, the vorticity field decays to zero on the lengthscales larger than ${\ell }_d$. We show that the self-propulsion velocity of $+1/2$ defects grows with $R$ in small systems where $R<{\ell }_d$, while in the infinite system limit or when $R\gg {\ell }_d$, it approaches a constant value determined by ${\ell }_d$.

21 pages, 8 figures

References in corpus (6)

• Spontaneous motion in hierarchically assembled active matter
• Swarming and swirling in self-propelled polar granular rods
• Defect dynamics in active nematics
• Probing the shear viscosity of an active nematic
• Dynamics of active nematic defects on the surface of a sphere
• Polar Fluctuations Lead to Extensile Nematic Behavior in Confluent Tissues

Cited by in corpus (4)

• Spontaneous Self-Constraint in Active Nematic Flows
• A unified field theory of topological defects and non-linear local excitations
• Analytical model for the motion and interaction of two-dimensional active nematic defects
• Defect configuration of an active nematic around a circular obstacle