Electrified coating flows on vertical fibres: enhancement or suppression of interfacial dynamics

Abstract

AbstractWe investigate the evolution and stability of a wetting viscous fluid layer flowing down the surface of a cylinder, and surrounded by a conductive gas. The inner cylinder is an electrode kept at constant voltage, and a second, concentric electrode encloses the system whose potential is allowed to vary spatially. This induces electrostatic forces at the interface in competition with surface tension and viscous stresses. Asymptotic methods are used to derive a long-wave axisymmetric model governing the interfacial position and charge density. The resulting system of equations is investigated both analytically and numerically to determine its stability characteristics in the linear and nonlinear regimes.