Observation of two coupled Faraday waves in a vertically vibrating Hele-Shaw cell with one of them oscillating horizontally

TL;DR

This paper reports the experimental observation of a novel coupled Faraday wave system in a Hele-Shaw cell, where one wave vibrates vertically and the other oscillates horizontally, revealing complex coupling and wave behavior.

Contribution

The study presents the first experimental observation of two coupled Faraday waves with distinct oscillation modes in a Hele-Shaw cell, highlighting their strong coupling and unique wave dynamics.

Findings

Upper and lower Faraday waves coexist with different oscillation modes.

Wave height of the lower wave is linearly or parabolically related to the upper wave.

The upper wave exhibits temporary loss of smoothness at specific phases.

Abstract

A system of two-dimensional, two coupled Faraday interfacial waves is experimentally observed at the two interfaces of the three layers of fluids (air, pure ethanol and silicon oil) in a sealed Hele-Shaw cell with periodic vertical vibration. The upper and lower Faraday waves coexist: the upper vibrates vertically, but the crests of the lower one oscillate horizontally with unchanged wave height and a frequency equal to the half of the forcing one of the vertically vibrating basin, while the troughs of the lower one always stay in the same place (relative to the basin). Besides, they are strongly coupled: the wave height of the lower Faraday wave is either a linear function (in the case of a fixed forcing frequency) or a parabolic function (in the case of a fixed acceleration amplitude) of that of the upper, with the same wave length. In addition, the upper Faraday wave temporarily loses its smoothness at around $t=T/4$ and $t=3T/4$, where $T$ denotes the wave period, and thus has fundamental difference from the traditional one. To the best of our knowledge, this system of the two coupled Faraday waves has never been reported.