An experimental study of the pattern formation in forced surface waves

Pattern formation in forced surface waves occurs between two layers of immiscible fluids of different densities, in which a vertical vibration is imposed, leading to stationary waves. This experimental study focuses primarily on the formation of the various wave patterns (solitary waves and meniscus waves) and the onset of Faraday waves. Three control parameters are varied to produce different flow patterns: the forcing amplitude and frequency as well as the depth (A(f), omega(f), Gamma). In this paper, we investigate low forcing frequencies ranging from 3 to 5 Hz, and high forcing amplitudes ranging from 3 to 15 mm. The measured responses correspond to the oscillation frequencies of the free surface omega(s) and their associated wavelength lambda(s). It is found that a succession of equilibrium states occurs spatially periodic structures and symmetric up to well-defined thresholds. Beyond these thresholds, symmetrical structures are broken and may follow two different paths: chaos follows the onset of the cross of Saint Andrew (meniscus wave) occupying all of the diagonal or an unstable pattern in the form of an odd polygon.