Fourier Amplitude Distribution and Intermittency in Mechanically Generated Surface Gravity Waves

We examine and discuss the spatial evolution of the statistical properties of mechanically generated surface gravity wave fields, initialised with unidirectional spectral energy distributions, uniformly distributed phases and Rayleigh distributed amplitudes. We demonstrate that nonlinear interactions produce an energy cascade towards high frequency modes with a directional spread and triggers localised intermittent bursts. By analysing the probability density function of Fourier mode amplitudes in the high frequency range of the wave energy spectrum, we show that a heavy-tailed distribution emerges with distance from the wave generator as a result of these intermittent bursts, departing from the originally imposed Rayleigh distribution, even under relatively weak nonlinear conditions.