The effect of induced flow on the water wave skewness

Physics of Fluids. 2025. Vol. 37. No. 8. Article 087192.

Slunyaev A., Kokorina A.

Nonlinear wave-induced perturbations are discussed within the framework of the second-order theory. Due to the slow attenuation of the long perturbations with depth, they modulate motions beneath surface waves down to the bottom and can strongly affect the wave statistics. The disturbance which corresponds to the second harmonic, at a sufficient depth, inverses the phase, thereby qualitatively changing the shape of individual waves. The skewness coefficients of the surface displacement and the bottom pressure fluctuations are considered. It is shown that the bottom pressure skewness may have different signs and magnitudes depending on the water depth and the configuration of nonlinear
wave groups that compose the wave field. The effect on the surface displacement skewness is much weaker. Mechanisms leading to strong deviation of the skewness coefficient from the nonlinear Stokes wave theory are discussed.

Keywords: асимметрия, донное давление, skewness, морские волны, bottom pressure, in-situ data, натурные измерения, direct numerical simulation, surface sea waves, прямое численное моделирование