Gravity-capillary waves on the free surface of a liquid dielectric in a tangential electric field

TL;DR

This study numerically investigates nonlinear gravity-capillary waves on a liquid dielectric surface under a tangential electric field, revealing wave preservation, formation of discontinuities, and potential for capillary turbulence.

Contribution

It introduces a numerical simulation method for nonlinear wave interactions under electric fields and uncovers new phenomena like wave shape preservation and turbulence development.

Findings

Wave shapes tend to be preserved at large electric fields.

Counter-propagating waves can cause surface discontinuities and infinite curvature.

Electric field-induced wave interactions can lead to capillary turbulence.

Abstract

Processes of propagation and interaction of nonlinear gravity-capillary waves on the free surface of a deep non-conducting liquid with high dielectric constant under the action of a tangential electric field are numerically simulated. The computational method is based on the time-dependent conformal transformation of the region occupied by the fluid into a half-plane. In the limit of a strong electric field, when the gravitational and capillary forces are negligibly small, there exists an exact analytical solution of the electro-hydrodynamic equations describing propagation without distortions of nonlinear surface waves along (or against) the electric field direction. In the situation where gravity and capillarity are taken into account, the results of numerical simulations indeed show that, for large external field, the waves traveling in a given direction tend to preserve their shape. In the limit of a strong electric field, the interaction of counter-propagating waves leads to the formation of regions, where the electrostatic and dynamic pressures undergo a discontinuity, and the curvature of the surface increases infinitely. The Fourier spectrum of the surface perturbations tends to the power-law distribution (k^-2). In the case of a finite electric field, the wave interaction results in a radiation of massive cascade of small-scale capillary waves that causes the chaotic behavior of the system. The investigated mechanism of interaction between oppositely-traveling waves can enhance development of the capillary turbulence of the fluid surface.