An experimental investigation of incipient spilling breakers
20
Citation
30
Reference
10
Related Paper
Citation Trend
Abstract:
In the present paper, the profiles of incipient spilling breaking waves with wavelengths ranging from 10 to 120cm were studied experimentally in clean water. Short-wavelength breakers were generated by wind, while longer-wavelength breakers were generated by a mechanical wavemaker, using either a dispersive focusing or a sideband instability mechanism. The crest profiles of these waves were measured with a high-speed cinematic laser-induced fluorescence technique. For all the wave conditions reported herein, wave breaking was initiated with a capillary-ripple pattern as described in Duncan et al . ( J. Fluid Mech ., vol. 379, 1999, pp. 191–222). In the present paper, it is shown that at incipient breaking the crest shape is self-similar with two geometrical parameters that depend only on the slope of a particular point on the front face of the gravity wave. The scaling relationships appear to be universal for the range of wavelengths studied herein and hold for waves generated by mechanical wavemakers and by wind. The slope measure is found to be dependent on the wave phase speed and the rate of growth of the crest height prior to incipient breaking.Keywords:
Crest
In response to the growing need for robust validation data for Phillips (1985) breaking wave spectral framework, we contribute new field results observed from R/P FLIP for the breaking crest length distributions, Λ, during two different wind‐wave conditions, and breaking strength during one wind‐wave condition. The first experiment in Santa Barbara Channel had developing seas and the second experiment in the central Pacific Ocean south of Hawaii had mature seas. These are among the first experiments to use dissipation rate measurements probing up into the breaking crest together with simultaneous measurements of breaking crest length distributions. We directly measured the effective breaking strength parameter to be in mature seas with wave age, , of 40–47. We also found that the velocity scale of the breaking dissipation rate peak decreases with increasing wave age. Further, the breaking crest length spectrum falls off slower than the behavior predicted by Phillips (1985). The integrated dissipation rate was consistently higher for mature seas compared to developing seas due to higher energy and momentum fluxes from the wind.
Crest
Breaking strength
Wave height
Cite
Citations (20)
A theoretical model is presented for the probability distribution of wave crest amplitudes in severe seas states with wave breaking. As the severity of a sea state increases, nonlinearities cause an increase in the amplitudes of the largest wave crests with a subsequent modification of the distribution of wave crest amplitudes from the linear Rayleigh theory. In this paper, a theory for the probabilities of these nonlinear crest amplitudes is first reviewed based on earlier work. The further limitations on these nonlinear crest amplitudes by wave breaking are then considered. As a result, a theoretical model is presented to account for both: 1) the nonlinear increase in the highest wave crests, and 2) the selective reduction of some fraction of these high crests due to wave breaking. This model is then verified using several sets of laboratory data for severe breaking seas having approximate JONSWAP wave spectra.
Crest
Rayleigh distribution
Sea state
Cite
Citations (7)
The propagation,shoaling and breaking of solitary waves on mild slopes are simulated byboundary element method.In this paper,the criterion of breaking solitary waves on mild slopes is discussed.The criterion is that the ratio of horizontal velocity of water particles on the wave crest to wave celerity equalsone.However,the case that the ratio of horizontal velocity of water particles on the wave crest to wave ce-lerity is below one but the front face of wave profile becomes vertical is also considered as a breaking criteri-on.According to the above criteria,the breaking index for slopes 1:10 to 1:25 is studied.The result is com-pared to other researchers’.The deformation of solitary waves on slopes is discussed and the distribution offluid velocities at breaking is shown.
Crest
Wave shoaling
Shoaling and schooling
Cite
Citations (0)
A numerical model is developed to investigate the formation of ripples at high sediment transport rates in oscillatory flow. Allowance is made for the movement of the crest during the course of the cycle and for the difference in shear stress on mobile beds compared with fixed beds. Equilibrium ripple height and length are computed for a range of conditions. The curves obtained for ripple wavelength, ripple height-to-length ratio and bed planation show satisfactory agreement with experimental data. Empirical formulae are proposed in the light of the computed results
Crest
Allowance (engineering)
Cite
Citations (2)
Steepness-limited wave breaking is simulated in a fully nonlinear potential flow model and validated with laboratory data. Breaking onset is based on the ratio of horizontal particle velocity at the crest, relative to the crest velocity reaching a threshold value. A breaking dissipation model, where the non-dimensional breaking strength parameter is predicted based on the linear wave steepness is used. A new time-dependent dissipation is tested, and the breaking termination criterion is studied.
Crest
Breaking strength
Cite
Citations (0)
Crest
Flume
Reflection
Wave flume
Wave height
Intensity
Cite
Citations (57)
Accurate prediction of the onset and strength of breaking surface gravity waves is a long-standing problem of significant theoretical and applied interest. Recently, Barth\'el\'emy et al (https://doi.org/10.1017/jfm.2018.93) examined the energetics of focusing wave groups in deep and intermediate depth water and found that breaking and non-breaking regimes were clearly separated by the normalised energy flux, $B$, near the crest tip. Furthermore, the transition of $B$ through a generic breaking threshold value $B_\mathrm{th} \approx 0.85$ was found to precede visible breaking onset by up to one fifth of a wave period. This remarkable generic threshold for breaking inception has since been validated numerically for 2D and 3D domains and for shallow and shoaling water waves; however, there is presently no theoretical explanation for its efficacy as a predictor for breaking. This study investigates the correspondence between the parameter $B$ and the crest energy growth rate following the evolving crest for breaking and non-breaking waves in a numerical wave tank using a range of wave packet configurations. Our results indicate that the time rate of change of the $B$ is strongly correlated with the energy density convergence rate at the evolving wave crest. These findings further advance present understanding of the elusive process of wave breaking.
Crest
Energetics
Wave shoaling
Shoaling and schooling
Cite
Citations (1)
Accurate prediction of the onset and strength of breaking surface gravity waves is a long-standing problem of significant theoretical and applied interest. Recently, Barthelemy et al (this https URL) examined the energetics of focusing wave groups in deep and intermediate depth water and found that breaking and non-breaking regimes were clearly separated by the normalised energy flux, $B$, near the crest tip. Furthermore, the transition of $B$ through a generic breaking threshold value $B_\mathrm{th} \approx 0.85$ was found to precede visible breaking onset by up to one fifth of a wave period. This remarkable generic threshold for breaking inception has since been validated numerically for 2D and 3D domains and for shallow and shoaling water waves; however, there is presently no theoretical explanation for its efficacy as a predictor for breaking. This study investigates the correspondence between the parameter $B$ and the crest energy growth rate following the evolving crest for breaking and non-breaking waves in a numerical wave tank using a range of wave packet configurations. Our results indicate that the time rate of change of the $B$ is strongly correlated with the energy density convergence rate at the evolving wave crest. These findings further advance present understanding of the elusive process of wave breaking.
Crest
Energetics
Wave shoaling
Shoaling and schooling
Cite
Citations (0)
The principal aim of this work is to quantify the long period (group) time scales associated with incident wave breaking in the surf zone. A video based sampling technique is employed to distinguish those waves which are breaking from those which are not. The technique relies on the gray tone contrast between higher luminance of turbulent generated bubbles and foam associated with wave breaking, and the darker, unbroken surrounding water. Video image intensity time series, I(x,y,t), are sampled across the width of the surf zone at 10 m increments, from just outside the shore break to the far offshore region of the wave breaking. Outside the point of minimum depth (at the bar crest), the width of the surf zone fluctuates over several hundred meters. In this region, low frequency oscillations in /, phase coupled to the crest of breaking incident waves, are associated with wave groups. Crossshore phase relationships indicate a shoreward progressive group structure up to the crest of the bar. Landward of the bar crest in the trough, low frequencies in / are uncoupled from group modulations seaward of the bar. Video data also show that wave breaking does not cease immediately as waves propagate past the bar crest, but continues well into the deeper water of the trough.
Crest
Trough (economics)
Surf zone
Bar (unit)
Significant wave height
Cite
Citations (2)