Dynamics of 2D Active Nematics Confined in an Annulus*

Active nematics are a class of non-equilibrium systems with constituents that consume energy
at the molecular level to generate motion. While the dynamics of a bulk 2D active nematic are
turbulent, confinement can provide a systematic way of achieving control over the flow. An
annulus confinement geometry is particularly interesting because it could generate self-driven
circulating flows. Indeed, such states have been found in recent experiments. In this talk, we will
discuss a theoretical and computational study of 2D active nematics confined to an annulus. By
performing simulations and comparing results against experiments as a function of geometry,
boundary conditions and activity, we identify the driving forces and factors that control net
circulation. In addition, by comparing the spatiotemporal behaviors as a function of annulus
geometry with those observed in a channel, we elucidate the effect of boundary curvature on
emergent behaviors in an active nematic.