![]() ![]() The standard approach to this problem is to combine the classical Stokes drift due to linear irrotational surface waves ( Kenyon 1969) with estimates of the wind drift, often based on laboratory experiments correlated with the wind friction velocity ( Wu 1975, 1982 Mueller and Veron 2009). Furthermore, there are significant practical applications in predicting the transport of flotsam, jetsam, and pollution at the surface. In the case of Langmuir circulations, their generation and evolution comes about primarily from Kelvin’s circulation theorem and the vorticity of the wind-driven current. Lagrangian drift at the ocean surface plays a fundamental role in the kinematics and dynamics of the surface layers of the ocean. The drift induced by wave breaking becomes increasingly more important with increasing wind friction velocity and increasing significant wave height. ![]() It is found that breaking may contribute up to an additional 30% to the predicted values of the classical Stokes drift of the wave field for the field experiments considered here, which have wind speeds ranging from 1.6 to 16 m s −1, significant wave heights in the range of 0.7–4.7 m, and wave ages (defined here as c m/ u *, for the spectrally weighted phase velocity c m and the wind friction velocity u *) ranging from 16 to 150. This model for the drift due to an individual breaking wave, together with the statistics of wave breaking measured in the field, are used to compute the Lagrangian drift of breaking waves in the ocean. found that the wave-breaking-induced mass transport, or drift, at the surface for a single breaking wave scales linearly with the slope of a focusing wave packet, and may be up to an order of magnitude larger than the prediction of the classical Stokes drift. Using direct numerical simulations (DNS), Deike et al. (2017b), while the star is an experimental measurement from Grue and Kolaas (2017). Diamonds and circles are DNS data from Deike et al. For the waves break, and the drift grows linearly with S and is described by the model proposed by Deike et al. For, the waves do not break and the drift is well described by the classical theory of Stokes drift, which predicts the drift grows quadratically with S. (b) For particles originally at the surface, the normalized Lagrangian drift induced by waves, where c is a characteristic phase speed, as a function of the linear prediction of the maximum slope at focusing S, a measure of the strength of breaking for, for a breaking threshold found here to be 0.31. Note, the particles are always in the water in these cases, never leaving it as spray. Particles travel much further in the case of a breaking wave. (a) Particle trajectories in a (top) nonbreaking and (bottom) breaking deep-water surface wave, from the DNS of Deike et al.
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