The flow generated by the breaking of free-surface waves in a periodic domain is simulated numerically with a gas–liquid Navier–Stokes solver. The solver relies on the volume-of-fluid method to account for different phases, and the interface tracking is carried out by using novel schemes based on a tailored total-variation-diminishing limiter. The numerical solver is proved to be characterized by a low numerical dissipation, thanks to the use of a scheme that guarantees energy conservation in the discrete form. Both two- and three-dimensional simulations have been performed, and the analysis is presented in terms of energy dissipation, air entrainment, bubble fragmentation, statistics and distribution. Particular attention is paid to the analysis of the mechanisms of viscous dissipation. To this purpose, coherent vortical structures, such as vortex tubes and vortex sheets, are identified, and the different behaviours of the vortex sheets and tubes at various Reynolds numbers are highlighted. The correlation between vortical structures and energy dissipation demonstrates clearly their close link both in the mixing zone and in the pure water domain, where the coherent structures propagate as a consequence of the downward transport. Notably, it is found that the dissipation is identified primarily by the vortex sheets, whereas the vortex tubes govern mainly the intermittency.

On coherent vortical structures in wave breaking / DI GIORGIO, Simone; Pirozzoli, Sergio; Iafrati, Alessandro. - In: JOURNAL OF FLUID MECHANICS. - ISSN 1469-7645. - 947:(2022). [10.1017/jfm.2022.674]

On coherent vortical structures in wave breaking

Simone Di Giorgio
;
Sergio Pirozzoli;Alessandro Iafrati
2022

Abstract

The flow generated by the breaking of free-surface waves in a periodic domain is simulated numerically with a gas–liquid Navier–Stokes solver. The solver relies on the volume-of-fluid method to account for different phases, and the interface tracking is carried out by using novel schemes based on a tailored total-variation-diminishing limiter. The numerical solver is proved to be characterized by a low numerical dissipation, thanks to the use of a scheme that guarantees energy conservation in the discrete form. Both two- and three-dimensional simulations have been performed, and the analysis is presented in terms of energy dissipation, air entrainment, bubble fragmentation, statistics and distribution. Particular attention is paid to the analysis of the mechanisms of viscous dissipation. To this purpose, coherent vortical structures, such as vortex tubes and vortex sheets, are identified, and the different behaviours of the vortex sheets and tubes at various Reynolds numbers are highlighted. The correlation between vortical structures and energy dissipation demonstrates clearly their close link both in the mixing zone and in the pure water domain, where the coherent structures propagate as a consequence of the downward transport. Notably, it is found that the dissipation is identified primarily by the vortex sheets, whereas the vortex tubes govern mainly the intermittency.
2022
numerical simulation; wave breaking; ocean dynamics
01 Pubblicazione su rivista::01a Articolo in rivista
On coherent vortical structures in wave breaking / DI GIORGIO, Simone; Pirozzoli, Sergio; Iafrati, Alessandro. - In: JOURNAL OF FLUID MECHANICS. - ISSN 1469-7645. - 947:(2022). [10.1017/jfm.2022.674]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1666126
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