Defect dynamics of 3D active nematic turbulence

Three-dimensional active nematics are exciting new materials characterized by a network of continuously evolving defect lines and loops [1]. We report on detailed numerical investigation of confined 3D active nematics [2]. At sufficient activity, such system transitions into active turbulence with irregular dynamics of multiple defect loops with distinct topological events of loop crossover, annihilation, splitting and merging occurring in time. The dynamics of a single active defect loop depends on the local crosssection of the director profile that can span from +1/2 or -1/2 winding numbers to twist profiles. Depending on the loop orientational profile, we observe spontaneous shrinking, growing, and bending of a single zero-charge loop [3]. Our work aims to provide insight into 3D active turbulence from the perspective of the topology of the emergent 3D defects and their self-induced dynamics.

[1] G Duclos et al, Topological structure and dynamics of three dimensional active nematics, arXiv:1909.01381, 2019.
[2] S Copar, J Aplinc, Z Kos, S Zumer and M Ravnik, Topology of Three-Dimensional Active Nematic Turbulence Confined to Droplets, Phys. Rev. X 9, 031051, 2019.
[3] J Binysh, Z Kos, S Copar, M Ravnik, GP. Alexander, Three-Dimensional Active Defect Loops, arXiv:1909.07109, 2019.