On the Nonlinear Coupling between Swell and Wind Waves

Publisher Website
Google Scholar
Abstract
The effect of nonlinear coupling due to resonant interactions on a bimodal spectrum is examined in the case of deep-water waves. Following Hasselmann, a swell decay time scale is first estimated for a monochromatic swell coupled with a typical wind wave spectrum. This time scale indicates that the nonlinear coupling generally causes the swell to decay at a rate that decreases rapidly as the swell frequency moves away from the peak frequency of the short waves. It is also shown, however, that the coupling makes the swell grow at the expense of the local sea in the frequency range just below the peak frequency of the short waves. Estimation of the nonlinear transfer for a swell of finite bandwidth confirms these results and also indicates a maximum coupling when the swell direction is about 40° to the mean direction of the short waves. When a double peaked spectrum is time integrated under the influence of the nonlinear interactions, the spectral distribution gradually changes into a unimodal shape... Abstract The effect of nonlinear coupling due to resonant interactions on a bimodal spectrum is examined in the case of deep-water waves. Following Hasselmann, a swell decay time scale is first estimated for a monochromatic swell coupled with a typical wind wave spectrum. This time scale indicates that the nonlinear coupling generally causes the swell to decay at a rate that decreases rapidly as the swell frequency moves away from the peak frequency of the short waves. It is also shown, however, that the coupling makes the swell grow at the expense of the local sea in the frequency range just below the peak frequency of the short waves. Estimation of the nonlinear transfer for a swell of finite bandwidth confirms these results and also indicates a maximum coupling when the swell direction is about 40° to the mean direction of the short waves. When a double peaked spectrum is time integrated under the influence of the nonlinear interactions, the spectral distribution gradually changes into a unimodal shape...

This publication has 0 references indexed in Scilit: