WAVE TRANSMISSION OVER LOW-CRESTED POROUS BREAKWATERS

Low-crested (LC) rubble mound breakwaters are used for coastal protection. The main advantage of these structures is their mild aesthetic impact on the natural environment. As the waves approach and transmit over these structures, significant hydrodynamic processes occur in their proximal area, such as wave breaking, wave reflection, wave overtopping and transmission (Garcia et al., 2004). Many researchers have studied the hydrodynamics of flow in the vicinity of such structures, as well as the influence of their geometrical characteristics on the flow field. However, in most studies, the structures are either emerged or submerged, while the case in which the crest level of the breakwaters is at the still water level (SWL) has to be further investigated.

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Wave-Follower Field Measurements of the Wind-Input Spectral Function. Part III: Parameterization of the Wind-Input Enhancement due to Wave Breaking

Journal of Physical Oceanography ◽

10.1175/2007jpo3757.1 ◽

2007 ◽

Vol 37 (11) ◽

pp. 2764-2775 ◽

Cited By ~ 34

Author(s):

Alexander V. Babanin ◽

Michael L. Banner ◽

Ian R. Young ◽

Mark A. Donelan

Keyword(s):

Energy Flux ◽

Water Waves ◽

Wave Breaking ◽

Field Measurements ◽

Mean Value ◽

Breaking Wave ◽

Strong Wind ◽

Local Wave ◽

Wind Input ◽

The Waves

Abstract This is the third in a series of papers describing wave-follower observations of the aerodynamic coupling between wind and waves on a large shallow lake during the Australian Shallow Water Experiment (AUSWEX). It focuses on the long-standing problem of the aerodynamic consequences of wave breaking on the wind–wave coupling. Direct field measurements are reported of the influence of wave breaking on the wave-induced pressure in the airflow over water waves, and hence the energy flux to the waves. The level of forcing, measured by the ratio of wind speed to the speed of the dominant (spectral peak) waves, covered the range of 3–7. The propagation speeds of the dominant waves were limited by the water depth and the waves were correspondingly steep. These measurements allowed an assessment of the magnitude of any breaking-induced enhancement operative for these field conditions and provided a basis for parameterizing the effect. Overall, appreciable levels of wave breaking occurred for the strong wind forcing conditions that prevailed during the observational period. Associated with these breaking wave events, a significant phase shift is observed in the local wave-coherent surface pressure. This produced an enhanced wave-coherent energy flux from the wind to the waves with a mean value of 2 times the corresponding energy flux to the nonbreaking waves. It is proposed that the breaking-induced enhancement of the wind input to the waves can be parameterized by the sum of the nonbreaking input and the contribution due to the breaking probability.

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Statistical Characteristics of Wave Breakings and their Relation with the Wind Waves’ Energy Dissipation Based on the Field Measurements

Morskoy gidrofizicheskiy zhurnal ◽

10.22449/0233-7584-2020-5-514-531 ◽

2020 ◽

Vol 36 (5) ◽

Author(s):

A. E. Korinenko ◽

V. V. Malinovsky ◽

V. N. Kudryavtsev ◽

V. A. Dulov ◽

◽

...

Keyword(s):

Energy Dissipation ◽

Wind Speed ◽

Wave Breaking ◽

Wind Waves ◽

Field Measurements ◽

Sea Surface ◽

Breaking Wave ◽

Movement Velocity ◽

Wide Range ◽

The Waves

Purpose. The work is aimed at studying geometric similarity of wind wave breakings in natural conditions, estimating the Duncan constant which connects the wave energy dissipation conditioned by wave breakings, with distribution of the lengths of a breaking wave crests Λ(с). Methods and Results. The field measurements of the wave breaking characteristics were carried out at the stationary oceanographic platform located in the Golubaya Bay near the village Katsiveli. Geometric dimensions of the wave breakings’ active phase, velocities and directions of their movement were determined from the video records of the sea surface; simultaneously, the meteorological information was recorded and the surface waves’ characteristics were measured. Altogether 55 video records of the sea surface were obtained; duration of each of them was 40–60 minutes. The measurements were performed in a wide range of meteorological conditions and wave parameters (wind speed varied from 9.2 to 21.4 m/s). Conclusions. It is found that the probability densities of the ratio between the maximum length of a breaking and the length of a breaking wave, obtained in various wind and wave conditions are similar. The average value of this ratio is 0.1. Distributions of the wave breakings’ total length are constructed in the movement velocity intervals on a surface unit. It is shown that the experimental estimates of dependence of these distributions upon the wind speed and the wave breaking movement velocity are consistent with the theoretical predictions of O.M. Phillips (1985); at that no dependence on the waves’ age was found. Quantitative characteristics of the relation between the wave lengths’ distribution and the energy dissipation are obtained. The Duncan constant was estimated; it turned out to be equal to 1.8⋅10-3 and independent upon the waves’ and atmosphere parameters.

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Investigation on the Reflection Coefficient for Seawalls Protected by a Rubble Mound Structure

Journal of Marine Science and Engineering ◽

10.3390/jmse9090937 ◽

2021 ◽

Vol 9 (9) ◽

pp. 937

Author(s):

Luigi Pratola ◽

Antonio Rinaldi ◽

Matteo Gianluca Molfetta ◽

Maria Francesca Bruno ◽

Davide Pasquali ◽

...

Keyword(s):

Reflection Coefficient ◽

Wave Reflection ◽

Experimental Tests ◽

Coastal Protection ◽

Empirical Formulas ◽

New Approach ◽

Wave Flume ◽

Mound Structure ◽

Rubble Mound ◽

Rubble Mound Breakwaters

Sea wave reflection from coastal protection structures is one of the main issues in the coastal design process. Several empirical formulas have been proposed so far to predict reflection coefficient from rubble mound breakwaters and smooth slopes. The aim of this study is to investigate wave reflection from a rubble mound structure placed in front of a vertical concrete seawall. Several experimental tests were performed on a two-dimensional wave flume by reproducing on a rubble mound structure with a steep single primary layer armored with a novel artificial unit. A new approach for the prediction of the reflection coefficient based on dimensional analysis is also proposed, and a new empirical equation is derived. The performance of the proposed equation was compared with widespread existing formulas, and a good accuracy was found.

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Statistical Characteristics of Wave Breakings and their Relation with the Wind Waves’ Energy Dissipation Based on the Field Measurements

Physical Oceanography ◽

10.22449/1573-160x-2020-5-472-488 ◽

2020 ◽

Vol 27 (5) ◽

Author(s):

A. E. Korinenko ◽

V. V. Malinovsky ◽

V. N. Kudryavtsev ◽

V. A. Dulov ◽

◽

...

Keyword(s):

Energy Dissipation ◽

Wind Speed ◽

Wave Breaking ◽

Wind Waves ◽

Field Measurements ◽

Sea Surface ◽

Breaking Wave ◽

Movement Velocity ◽

Wide Range ◽

The Waves

Purpose. The work is aimed at studying geometric similarity of wind wave breakings in natural conditions, estimating the Duncan constant which connects the wave energy dissipation conditioned by wave breakings, with distribution of the lengths of a breaking wave fronts Λ(с). Methods and Results. The field measurements of the wave breaking characteristics were carried out at the stationary oceanographic platform located in the Golubaya Bay near the Katsiveli village. Geometric dimensions of the wave breakings’ active phase, velocities and directions of their movement were determined from the video records of the sea surface; simultaneously, the meteorological information was recorded and the surface waves’ characteristics were measured. Altogether 55 video recordings (duration 40–50 mins) of the sea surface were obtained. The measurements were carried out in a wide range of meteorological conditions and wave parameters (wind speed varied from 9.2 to 21.4 m/s). Conclusions. It is found that the probability densities of the ratio between the maximum length of a breaking and the length of a breaking wave, obtained in various wind and wave conditions are similar. The average value of this ratio is 0.1. Distributions of the wave breakings’ total length are constructed in the movement velocity intervals on a surface unit. It is shown that the experimental estimates of dependence of these distributions upon the wind speed and the wave breaking movement velocity are consistent with the theoretical predictions of O.M. Phillips (1985); at that no dependence on the waves’ age was found. Quantitative characteristics of the relation between the wave lengths’ distribution and the energy dissipation are obtained. The Duncan constant was estimated; it turned out to be equal to 1.8·10-3 and independent upon the waves’ and atmosphere parameters.

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PHYSICAL INTERPRETATION OF WAVE BREAKING CRITERIA

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b94019210f7.30842240 ◽

2017 ◽

Author(s):

Sergey Kuznetsov ◽

Yana Saprykina ◽

Boris Divinskiy ◽

...

Keyword(s):

Nonlinear Wave ◽

Wave Breaking ◽

Second Harmonic ◽

Vertical Axis ◽

Breaking Waves ◽

Wave Transformation ◽

Spectral Structure ◽

Similarity Parameter ◽

Nonlinear Harmonics ◽

The Waves

On the base of experimental data it was revealed that type of wave breaking depends on wave asymmetry against the vertical axis at wave breaking point. The asymmetry of waves is defined by spectral structure of waves: by the ratio between amplitudes of first and second nonlinear harmonics and by phase shift between them. The relative position of nonlinear harmonics is defined by a stage of nonlinear wave transformation and the direction of energy transfer between the first and second harmonics. The value of amplitude of the second nonlinear harmonic in comparing with first harmonic is significantly more in waves, breaking by spilling type, than in waves breaking by plunging type. The waves, breaking by plunging type, have the crest of second harmonic shifted forward to one of the first harmonic, so the waves have "saw-tooth" shape asymmetrical to vertical axis. In the waves, breaking by spilling type, the crests of harmonic coincides and these waves are symmetric against the vertical axis. It was found that limit height of breaking waves in empirical criteria depends on type of wave breaking, spectral peak period and a relation between wave energy of main and second nonlinear wave harmonics. It also depends on surf similarity parameter defining conditions of nonlinear wave transformations above inclined bottom.

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Characteristics of Breaking Wave Forces on Piles over a Permeable Seabed

Journal of Marine Science and Engineering ◽

10.3390/jmse9050520 ◽

2021 ◽

Vol 9 (5) ◽

pp. 520

Author(s):

Zhenyu Liu ◽

Zhen Guo ◽

Yuzhe Dou ◽

Fanyu Zeng

Keyword(s):

Wave Breaking ◽

Stokes Equations ◽

Slope Angle ◽

Wave Force ◽

Breaking Waves ◽

Offshore Wind ◽

Secondary Wave ◽

Wave Forces ◽

Breaking Wave ◽

Breaking Wave Forces

Most offshore wind turbines are installed in shallow water and exposed to breaking waves. Previous numerical studies focusing on breaking wave forces generally ignored the seabed permeability. In this paper, a numerical model based on Volume-Averaged Reynolds Averaged Navier–Stokes equations (VARANS) is employed to reveal the process of a solitary wave interacting with a rigid pile over a permeable slope. Through applying the Forchheimer saturated drag equation, effects of seabed permeability on fluid motions are simulated. The reliability of the present model is verified by comparisons between experimentally obtained data and the numerical results. Further, 190 cases are simulated and the effects of different parameters on breaking wave forces on the pile are studied systematically. Results indicate that over a permeable seabed, the maximum breaking wave forces can occur not only when waves break just before the pile, but also when a “secondary wave wall” slams against the pile, after wave breaking. With the initial wave height increasing, breaking wave forces will increase, but the growth can decrease as the slope angle and permeability increase. For inclined piles around the wave breaking point, the maximum breaking wave force usually occurs with an inclination angle of α = −22.5° or 0°.

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Wave Breaking in Undular Bores with Shear Flows

Water Waves ◽

10.1007/s42286-020-00046-6 ◽

2021 ◽

Author(s):

Maria Bjørnestad ◽

Henrik Kalisch ◽

Malek Abid ◽

Christian Kharif ◽

Mats Brun

Keyword(s):

Turbulent Flows ◽

Wave Breaking ◽

Vries Equation ◽

Kdv Equation ◽

Flow Depth ◽

Present Contribution ◽

Undular Bore ◽

Wave Flume ◽

The Kdv Equation ◽

The Waves

AbstractIt is well known that weak hydraulic jumps and bores develop a growing number of surface oscillations behind the bore front. Defining the bore strength as the ratio of the head of the undular bore to the undisturbed depth, it was found in the classic work of Favre (Ondes de Translation. Dunod, Paris, 1935) that the regime of laminar flow is demarcated from the regime of partially turbulent flows by a sharply defined value 0.281. This critical bore strength is characterized by the eventual breaking of the leading wave of the bore front. Compared to the flow depth in the wave flume, the waves developing behind the bore front are long and of small amplitude, and it can be shown that the situation can be described approximately using the well known Kortweg–de Vries equation. In the present contribution, it is shown that if a shear flow is incorporated into the KdV equation, and a kinematic breaking criterion is used to test whether the waves are spilling, then the critical bore strength can be found theoretically within an error of less than ten percent.

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Assessment of Numerical Methods for Plunging Breaking Wave Predictions

Journal of Marine Science and Engineering ◽

10.3390/jmse9030264 ◽

2021 ◽

Vol 9 (3) ◽

pp. 264

Author(s):

Shanti Bhushan ◽

Oumnia El Fajri ◽

Graham Hubbard ◽

Bradley Chambers ◽

Christopher Kees

Keyword(s):

Solitary Wave ◽

Wave Breaking ◽

Large Scale ◽

Turbulence Models ◽

Navier Stokes ◽

Wave Crest ◽

Breaking Wave ◽

Rans Turbulence Models ◽

Run Up ◽

Better Than

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

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