When surface waves are excited by a wavemaker,
localized transverse stationary waves, with crests approximately normal to the wavemaker, are frequently encountered
in addition to the expected longitudinal propagative waves.
These transverse waves, which received the name of cross-waves, oscillate at half the forcing frequency, indicating a parametric instability mechanism. They are stationnary along the wavemaker, but show a propagation away from it.
Original drawing by Michael Faraday (1831), showing the formation
of radial cross-waves at the
surface of water, excited by a cylindrical cork oscillating at large frequency. [Philos. Trans. Royal Soc., London 121,
Cross-waves generated by the vertical oscillation of a wavemaker crossing the interface. Note that the stationnary wave along the wavemaker has frequency half the forcing frequency. Oscillation frequency: 40 Hz.
3D reconstruction of the cross-wave, generated by the vertical oscillation of a fully immersed wavemaker. The surface reconstruction is obtained using Free-Surface Synthetic Schlieren.
Structure of the cross-wave pattern, showing the stationnary oscillation along the wavemaker (y direction) and the propagation away from it (x direction).
Crosswaves induced by the vertical oscillation of a fully immersed vertical plate
F. Moisy, G.-J. Michon, M. Rabaud, E. Sultan, Phys. Fluids24, 022110 (2012).
[Abstract | PDF | movies]
Unpredictable tunneling of a classical wave-particle association
A. Eddi, E. Fort, F. Moisy, Y. Couder, Phys. Rev. Lett.102, 240401 (2009).
[Abstract | PDF]
A Synthetic Schlieren method for the measurement of the topography of a liquid interface
F. Moisy, M. Rabaud, K. Salsac, Exp. in Fluids46 (6), 1021-1036 (2009).
[Abstract | PDF | applications | tutorial]