On coherent vortical structures in wave breaking

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...

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Bibliographic Details
Published in:Journal of fluid mechanics 2022-09, Vol.947, Article A44
Main Authors: Di Giorgio, Simone, Pirozzoli, Sergio, Iafrati, Alessandro
Format: Article
Language:English
Subjects:
Air entrainment
Bubbles
Coherence
Domains
Energy conservation
Energy dissipation
Energy exchange
Entrainment
Fluid flow
Free surfaces
Identification
Investigations
JFM Papers
Numerical analysis
Numerical dissipation
Reynolds number
Simulation
Solvers
Statistical analysis
Statistical methods
Structures
Surface waves
Tracking
Tubes
Vortex sheets
Wave breaking
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Summary: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.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2022.674