ICMCS seminar - Asymmetry in the Dynamics of Topological Defects in Active Nematics

Title: Asymmetry in the Dynamics of Topological Defects in Active Nematics

Abstract: In non-equilibrium active matter, such as reconstituted cytoskeletal networks and bacterial swarms, turbulent flows are governed by the dynamics of topological defects. While the properties of individual ±1/2 defects are known, the precise mechanism of their pairwise annihilation—the key process that regulates defect density and system dynamics—remains poorly understood.  To address this, we conducted high-resolution numerical experiments using a hybrid lattice Boltzmann method to simulate a 2D active nematic. We tracked and analyzed creation and annihilation events of topological defect pairs. This work examines the approach/departure dynamics, quantifies the surrounding flow, and tests the validity of purely elastic interaction models against full hydrodynamic simulations. Our simulations reveal a significant deviation from elastic theory and a persistent asymmetric structure in the vorticity field throughout annihilation events.  The findings establish that active defect annihilation is fundamentally mediated by activity-generated hydrodynamics. Incorporating this asymmetry into theoretical models may help to produce a better understanding of defect lifetimes and turbulent scaling laws. 

https://ed-ac-uk.zoom.us/j/81211470751

Meeting ID: 812 1147 0751
Passcode: ICMCS123