Generation of stripe-like vortex flow by noncollinear waves on the water surface

• Published in: Physica. D Vol. 434; p. 133218
• Main Authors: Filatov, S.V., Poplevin, A.V., Levchenko, A.A., Parfenyev, V.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2022
• Subjects: Insoluble film; Streaming pattern; Surface waves; Virtual wave stress; Vortex motion; Vortex motion; Surface waves; Virtual wave stress; Insoluble film; Streaming pattern
• ISSN: 0167-2789; 1872-8022
• DOI: 10.1016/j.physd.2022.133218

We have studied experimentally the generation of vortex flow by gravity waves with a frequency of 2.34Hz excited on the water surface at an angle 2θ=arctan(3/4)≈36∘ to each other. The resulting horizontal surface flow has a stripe-like spatial structure. The width of the stripes L=π/(2ksinθ) is determined by the wave vector k of the surface waves and the angle between them, and the length of the stripes is limited by the system size. It was found that the vertical vorticity Ω of the current on the fluid surface is proportional to the product of wave amplitudes, but its value is much higher than the value corresponding to the Stokes drift and it continues to grow with time even after the wave motion reaches a stationary regime. We demonstrate that the measured dependence Ω(t) can be described within the recently developed model that takes into account the Eulerian contribution to the generated vortex flow and the effect of surface contamination. This model contains a free parameter that describes the elastic properties of the contaminated surface, and we also show that the found value of this parameter is in reasonable agreement with the measured decay rate of surface waves. •Crossed surface waves generate streaming currents owing to hydrodynamic nonlinearity.•The spatial horizontal structure of streaming flow coincides with the Stokes drift.•Streaming currents are stronger than the Stokes drift at sufficiently long times.•Surface contamination can be modeled by the presence of a thin insoluble liquid film.•Surface film intensifies streaming currents and increases the wave damping.