On the observability of finite-depth short-crested water waves

Abstract:

A numerical study of the superharmonic instabilities of short-crested waves on water of finite depth is performed in order to measure their time scales. It is shown that these superharmonic instabilities can be significant - unlike the deep-water case - in parts of the parameter regime. New resonances associated with the standing wave limit are studied closely. These instabilities 'contaminate' most of the parameter space, excluding that near two-dimensional progressive waves; however, they are significant only near the standing wave limit. The main result is that very narrow bands of both short-crested waves 'close' to two-dimensional standing waves, and of well developed short-crested waves, perturbed by superharmonic instabilities, are unstable for depths shallower than approximately a non-dimensional depth d = 1; the study is performed down to depth d = 0.5 beyond which the computations do not converge sufficiently. As a corollary, the present study pbkp_redicts that these very narrow sub-domains of shortcrested wave fields will not be observable, although most of the short-crested wave fields will be.

Año de publicación:

1996

Keywords:

Fuente:

scopus