Vortex generation by deep-water breaking waves

TitleVortex generation by deep-water breaking waves
Publication TypeJournal Article
Year of Publication2013
AuthorsPizzo N.E, Melville W.K
JournalJournal of Fluid Mechanics
Date Published2013/11
Type of ArticleArticle
ISBN Number0022-1120
Accession NumberWOS:000325817200012
Keywordsair/sea interactions; breakers; energy-dissipation; field; flow; langmuir circulations; model; turbulence; vortex flows; wave breaking

The connection between wave dissipation by breaking deep-water surface gravity waves and the resulting turbulence and mixing is crucial for an improved understanding of air-sea interaction processes. Starting with the ensemble-averaged Euler equations, governing the evolution of the mean flow, we model the forcing, associated with the breaking-induced Reynolds shear stresses, as a body force describing the bulk scale effects of a breaking deep-water surface gravity wave on the water column. From this, we derive an equation describing the generation of circulation, Gamma of the ensemble-average velocity field, due to the body force. By examining the relationship between a breaking wave and an impulsively forced fluid, we propose a functional form for the body force, allowing us to build upon the classical work on vortex ring phenomena to both quantify the circulation generated by a breaking wave and describe the vortex structure of the induced motion. Using scaling arguments, we show that Gamma = alpha(hk)(3/2)c(3)/g, where (c, h, k) represent a characteristic speed, height and wavenumber of the breaking wave, respectively, g is the acceleration due to gravity and alpha is a constant. This then allows us to find a direct relationship between the circulation and the wave energy dissipation rate per unit crest length due to breaking, epsilon(l). Finally, we compare our model and the available experimental data.

Short TitleJ. Fluid Mech.
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