Experimental Studies of Strong Nonlinear Interactions of Deep-Water Gravity Waves
Results of an extensive series of experiments on strong nonlinear interactions of deep and shallow gravity waves are summarized. The experiments are conducted in a large outdoor basin and a long indoor wave tank. The waves are produced by a mechanical wavemaker or by natural wind in some cases in the outdoor basin. The effects of steepness (0.1 ≲ ak ≲ 0.34) are analyzed for both wave trains and packets. Waves with moderate to large steepness (ak ≲ 0.25) are found to be subject to intense subharmonic instabilities. Dynamical processes observed in these experiments include subharmonic instabilities, wave breaking, directional energy spreading, nonlinear energy transfer in narrow spectra, formation/interactions of envelope solitons, and formation of other three-dimensional compact wave groups of permanent forms. Effects of water depth on some of the above nonlinear processes are also considered. The experimental investigations plus analyses of other oceanic measurements and theoretical computations seem to imply that the classical view of weak-in-the-mean interactions of ocean waves can also be explained conceptually by combined effects of intermittent processes of strong three-dimensional nonlinear interactions of various kinds.
KeywordsWave Packet Gravity Wave Wave Train Breaking Wave Wave Group
Unable to display preview. Download preview PDF.
- Chappelear, J. E. (1961): On the description of short-crested waves. Beach Erosion Board, Office of the Chief of Engineers, T.M. 125. U.S. Army Corps of Engineers, Washington, D.C.Google Scholar
- Longuet-Higgins, M. S. (1976): On the nonlinear transfer of energy in the peak of a gravity-wave spectrum: A simplified model. Proc. R. Soc. London Ser. A 347, 331–338.Google Scholar
- Zakharov, V. E. (1968): Stability of periodic waves of finite ampHtude on the surface of a deep fluid. J. Appl. Mech. Tech. Phys. (USSR) 2, 190–194.Google Scholar