An energetic signature for breaking inception in surface gravity waves

Boettger, Daniel; Keating, Shane R.; Banner, Michael L.; Morison, Russel P.; Barthelemy, Xavier

doi:10.1017/jfm.2023.134

Cited by 4 publications

(4 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The times at which are similar to the times at which in figure 10 of Boettger et al. (2023). Thus, there may be a link between a surface-slope-based and an energy-based signature of breaking inception.…”

Section: Fully Nonlinear Numerical Simulationssupporting

confidence: 85%

“…Similarity in the crest shape of breaking waves may be linked to a kinematic description of breaking (and, thus, to a given value of or (Boettger et al. 2023)) which, alongside the robustness and generality of a slope-based threshold, should be examined further.…”

Section: Discussionmentioning

confidence: 99%

“…In a recent paper, Boettger et al. (2023) examined the flux of the maximum kinetic energy at the crest of breaking and non-breaking waves, and found that breaking occurred when for 2-D chirped wave packets on intermediate and deep water (). This threshold occurs approximately 0.25 periods prior to and may potentially be an indication of irreversible breaking inception, which precedes breaking onset.…”

Section: Fully Nonlinear Numerical Simulationsmentioning

confidence: 99%

“…In experiments performed using clean water, Diorio, Liu & Duncan (2009) observed PCW formation on spilling breaking waves that were generated by dispersive focusing with characteristic wavelengths as large as m. Boettger et al. (2023) performed computational fluid dynamics (CFD) simulations of 2-D breaking waves, concluding that the effects of surface tension were negligible on the energetics of breaking onset and that small amounts of viscous dissipation occurred at the wave crest ( m, ). The studies we have referenced above examine a mixture of breaking and non-breaking waves.…”

Section: Fully Nonlinear Numerical Simulationsmentioning

confidence: 99%

See 3 more Smart Citations

The influence of spectral bandwidth and shape on deep-water wave breaking onset

McAllister,

Pizzo,

Draycott

et al. 2023

J. Fluid Mech.

View full text Add to dashboard Cite

Deep-water surface wave breaking affects the transfer of mass, momentum, energy and heat between the air and sea. Understanding when and how the onset of wave breaking will occur remains a challenge. The mechanisms that form unforced steep waves, i.e. nonlinearity or dispersion, are thought to have a strong influence on the onset of wave breaking. In two dimensions and in deep water, spectral bandwidth is the main factor that affects the roles these mechanism play. Existing studies, in which the relationship between spectral bandwidth and wave breaking onset is investigated, present varied and sometimes conflicting results. We perform potential-flow simulations of two-dimensional focused wave groups on deep water to better understand this relationship, with the aim of reconciling existing studies. We show that the way in which steepness is defined may be the main source of confusion in the literature. Locally defined steepness at breaking onset reduces as a function of bandwidth, and globally defined (spectral) steepness increases. The relationship between global breaking onset steepness and spectral shape (using the parameters bandwidth and spectral skewness) is too complex to parameterise in a general way. However, we find that the local surface slope of maximally steep non-breaking waves, of all spectral bandwidths and shapes that we simulate, approaches a limit of $1/\tan ({\rm \pi} /3)\approx 0.5774$ . This slope-based threshold is simple to measure and may be used as an alternative to existing kinematic breaking onset thresholds. There is a potential link between slope-based and kinematic breaking onset thresholds, which future work should seek to better understand.

show abstract

Section: Fully Nonlinear Numerical Simulationssupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Fully Nonlinear Numerical Simulationsmentioning

confidence: 99%

Section: Fully Nonlinear Numerical Simulationsmentioning

confidence: 99%

See 2 more Smart Citations

The influence of spectral bandwidth and shape on deep-water wave breaking onset

McAllister,

Pizzo,

Draycott

et al. 2023

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

Three-dimensional wave breaking

McAllister,

Draycott,

Calvert

et al. 2024

Nature

View full text Add to dashboard Cite

Although a ubiquitous natural phenomenon, the onset and subsequent process of surface wave breaking are not fully understood. Breaking affects how steep waves become and drives air–sea exchanges1. Most seminal and state-of-the-art research on breaking is underpinned by the assumption of two-dimensionality, although ocean waves are three dimensional. We present experimental results that assess how three-dimensionality affects breaking, without putting limits on the direction of travel of the waves. We show that the breaking-onset steepness of the most directionally spread case is double that of its unidirectional counterpart. We identify three breaking regimes. As directional spreading increases, horizontally overturning ‘travelling-wave breaking’ (I), which forms the basis of two-dimensional breaking, is replaced by vertically jetting ‘standing-wave breaking’ (II). In between, ‘travelling-standing-wave breaking’ (III) is characterized by the formation of vertical jets along a fast-moving crest. The mechanisms in each regime determine how breaking limits steepness and affects subsequent air–sea exchanges. Unlike in two dimensions, three-dimensional wave-breaking onset does not limit how steep waves may become, and we produce directionally spread waves 80% steeper than at breaking onset and four times steeper than equivalent two-dimensional waves at their breaking onset. Our observations challenge the validity of state-of-the-art methods used to calculate energy dissipation and to design offshore structures in highly directionally spread seas.

show abstract