Investigation of resonances in gravity-capillary wave turbulence

TL;DR

This study experimentally investigates nonlinear wave interactions in water surface wave turbulence near the gravity-capillary crossover, revealing dominant collinear 3-wave couplings and nonlocal interactions between gravity and capillary waves.

Contribution

It provides new experimental insights into wave coupling mechanisms at the gravity-capillary scale, highlighting nonlocal interactions and spectral spreading effects.

Findings

Dominant collinear 3-wave interactions in weakly nonlinear regime

Nonlocal coupling between gravity and capillary waves observed

Spectral spreading enables 3-gravity wave coupling

Abstract

We report experimental results on nonlinear wave coupling in surface wave turbulence on water at scales close to the crossover between surface gravity waves and capillary waves. We study 3-wave correlations either in the frequency domain or in wavevector domain. We observe that in a weakly nonlinear regime, the dominant nonlinear interactions correspond to waves that are collinear or close to collinear. Although the resonant coupling of pure gravity waves is supposed to involve 4 waves, at the capillary crossover we observe a nonlocal coupling between a gravity wave and 2 capillary waves. Furthermore nonlinear spectral spreading permits 3-gravity wave coupling. These observations raise the question of the relevance of these processes in the oceanographic context and in particular the range of frequencies of gravity waves that may be impacted.