Hydrodynamic Effects in Oscillatory Active Nematics

Oscillatory active nematics represent nonequilibrium suspensions of microscopic objects, such as natural or artificial molecular machines, that cyclically change their shapes and thus operate as oscillating force dipoles. In this mini-review, hydrodynamic collective effects in such active nematics are discussed. Microscopic stirring at low Reynolds numbers induces non-thermal fluctuating flows and passive particles become advected by them. Similar to advection of particles in macroscopic turbulent flows, this enhances diffusion of tracer particles. Furthermore, their drift and accumulation in regions with stronger activity or higher concentration of force dipoles take place. Analytical investigations and numerical simulations both for 2D and 3D systems were performed.