Large-scale flow out of spatiotemporal chaos in electroconvection of cholesteric liquid crystal

Convection in a thin layer of liquid crystal driven by an electric field has long been studied as a model system to investigate pattern formation in out-of-equilibrium systems. In particular, it has been known that the flow typically shows spatiotemporal chaotic patterns called dynamic scattering mode with high voltage. In this presentation, we report our observation that this chaotic pattern organizes itself into a large-scale flow perpendicular to the electric field in the case where cholesteric liquid crystal with the negative dielectric constant difference is used. The typical scale of this flow pattern is more than 100 times larger than the distance between the electrodes, the characteristic length scale of the convection. We will discuss the effect of the anchoring and boundary conditions, and possible interpretation toward understanding the mechanism.