Formation of Vortex Motion by Capillary Waves on the Surface of Water

Abstract

The processes of the formation and decay of vortex motion on the surface of water are studied experimentally. The vortex motion is formed by capillary waves, which are generated as a result of harmonic oscillations of a cell with water in the vertical direction. It is shown that, at oscillation amplitudes smaller than the critical value, a vortex lattice with a period that is equal to the excitation wavelength is formed. The characteristic time of the formation and decay of vortex motion is close to the time of viscous damping of the pumping wave. At pumping amplitudes that are greater than the critical value, a vortex lattice is initially formed on the surface; then it is destroyed gradually by large-scale movements. The energy distribution over the wave vector can be described by a power function that is close to k^–5/3. It is suggested that large-scale vortex motion arises as a result of the interaction of low-frequency waves appearing on the surface as a consequence of the nonlinear interaction of waves.