Localized states in sheared electroconvection

TL;DR

This paper presents a numerical study of electroconvection in a sheared annular film, revealing complex bifurcations, localized vortex states, and chaos, providing insights into experimental observations of electroconvecting smectic films.

Contribution

The study introduces a detailed numerical model of sheared electroconvection in annular films, elucidating bifurcation sequences and flow states not accessible through experiments alone.

Findings

Localized vortex states near onset due to shear and electrical forces

Oscillatory and subcritical bifurcations observed in simulations

Transition to chaos via Ruelle-Takens-Newhouse scenario at higher forcing

Abstract

Electroconvection in a thin, sheared fluid film displays a rich sequence of bifurcations between different flow states as the driving voltage is increased. We present a numerical study of an annular film in which a radial potential difference acts on induced surface charges to drive convection. The film is also sheared by independently rotating the inner edge of the annulus. This simulation models laboratory experiments on electroconvection in sheared smectic liquid crystal films. The applied shear competes with the electrical forces, resulting in oscillatory and strongly subcritical bifurcations between localized vortex states close to onset. At higher forcing, the flow becomes chaotic via a Ruelle-Takens-Newhouse scenario. The simulation allows flow visualization not available in the physical experiments, and sheds light on previously observed transitions in the current-voltage characteristics of electroconvecting smectic films.