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

2007 ◽  
Vol 37 (11) ◽  
pp. 2764-2775 ◽  
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.

Wave-Follower Field Measurements of the Wind-Input Spectral Function. Part II: Parameterization of the Wind Input

2006 ◽  
Vol 36 (8) ◽  
pp. 1672-1689 ◽  
Author(s):  
Mark A. Donelan ◽  
Alexander V. Babanin ◽  
Ian R. Young ◽  
Michael L. Banner
Keyword(s):  
Water Waves ◽  
Source Function ◽  
Field Measurements ◽  
Wave Steepness ◽  
Outer Flow ◽  
Wide Range ◽  
Input Source ◽  
Wind Input ◽  
Wave Induced ◽  
The Waves

Abstract Nearly all of the momentum transferred from wind to waves comes about through wave-induced pressure acting on the slopes of waves: known as form drag. Direct field measurements of the wave-induced pressure in airflow over water waves are difficult and consequently rare. Those that have been reported are for deep water conditions and conditions in which the level of forcing, measured by the ratio of wind speed to the speed of the dominant (spectral peak) waves, is quite weak, U10/cp < 3. The data reported here were obtained over a large shallow lake during the Australian Shallow Water Experiment (AUSWEX). The propagation speeds of the dominant waves were limited by depth and the waves were correspondingly steep. This wider range of forcing and concomitant wave steepness revealed some new aspects of the rate of wave amplification by wind, the so-called wind input source function, in the energy balance equation for wind-driven water waves. It was found that the exponential growth rate parameter (fractional energy increase per radian) depended on the slope of the waves, ak, vanishing as ak → 0. For very strong forcing a condition of “full separation” occurs, where the airflow detaches from the crests and reattaches on the windward face leaving a separation zone over the leeward face and the troughs. In a sense, the outer flow does not “see” the troughs and the resulting wave-induced pressure perturbation is much reduced, leading to a reduction in the wind input source function relative to that obtained by extrapolation from more benign conditions. The source function parameterized on wave steepness and degree of separation is shown to be in agreement with previous field and laboratory data obtained in conditions of much weaker forcing and wave steepness. The strongly forced steady-state conditions of AUSWEX have enabled the authors to define a generalized wind input source function that is suitable for a wide range of conditions.

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

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.

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

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.

scholarly journals WAVE TRANSMISSION OVER LOW-CRESTED POROUS BREAKWATERS

2018 ◽  
pp. 15
Author(s):  
Theofano I. Koutrouveli ◽  
Athanassios A. Dimas
Keyword(s):  
Flow Field ◽  
Natural Environment ◽  
Wave Breaking ◽  
Wave Reflection ◽  
Coastal Protection ◽  
Breaking Wave ◽  
Geometrical Characteristics ◽  
Hydrodynamic Processes ◽  
Rubble Mound Breakwaters ◽  
The Waves

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.

Refining an Eddy Viscosity Model for Two-Dimensional Breaking Waves in Deep Water: Experiments

2011 ◽  
Author(s):  
Zhigang Tian ◽  
Wooyoung Choi ◽  
Marc Perlin
Keyword(s):  
Wave Breaking ◽  
Eddy Viscosity ◽  
Breaking Waves ◽  
Viscosity Model ◽  
Breaking Wave ◽  
Wave Groups ◽  
Eddy Viscosity Model ◽  
Wave Parameters ◽  
Local Wave ◽  
Breaking Time

This paper presents an experimental study of breaking waves in deep water, as part of the effort to further develop an eddy viscosity model for wave breaking, originally proposed by Tian, Perlin & Choi (2010, J. Fluid Mech. 655, 217–257). In the previous work, the wave breaking time, location, and breaking strength were required a priori for numerical simulations. It is our intention to make further refinement so that the improved eddy viscosity model automatically predicts wave breaking onset, determines local wave parameters at breaking onset, and forecasts post-breaking time and length scales to estimate the magnitude of the eddy viscosity. As the first part of the further development, we conducted wave breaking experiments, in which breaking wave groups are generated using both wave energy focusing and modulational instability. Surface elevations as a function of time are measured and surface profiles as a function of space during active breaking events are captured. Local wave parameters at wave breaking onset (pre-breaking parameters) are defined and determined, as well as the post-breaking time and length scales. Correlations among the parameters at breaking onset and the post-breaking scales are identified. Similarities and differences of the two types of breaking wave groups are provided and discussed.

Cyclic recurrence in nonlinear unidirectional ocean waves

1988 ◽  
Vol 192 ◽  
pp. 329-337 ◽  
Author(s):  
Peter J. Bryant
Keyword(s):  
Wave Breaking ◽  
Ocean Surface ◽  
Ocean Waves ◽  
Open Ocean ◽  
Nonlinear Interactions ◽  
Slow Time ◽  
Wave Groups ◽  
Stokes Waves ◽  
Local Wave ◽  
The Waves

A fully nonlinear model is developed for the unidirectional propagation of periodic gravity wave groups in deep water, in which the shape of the group envelopes changes cyclically. It is intended to describe the slow-time evolution of wave groups on the open ocean surface, and to generalize the cyclic recurrence that can occur during the sideband modulation of Stokes waves and Schrödinger wave groups. The weak nonlinear interactions are shown to concentrate the wave energy at the centre of each group at regular intervals, causing the waves there to be of greater height locally in space and time. This is suggested as one mechanism for the local wave breaking that is observed on the open ocean surface. The cyclically recurring wave groups may be interpreted as the limit-cycle stage in a progression from uniform wave groups to chaos on the forced, damped, ocean surface.

scholarly journals SURF ZONE WAVE HEATING BY ENERGY DISSIPATION OF BREAKING WAVES

2018 ◽  
pp. 2 ◽  
Author(s):  
Zhangping Wei ◽  
Robert A. Dalrymple
Keyword(s):  
Internal Energy ◽  
Wave Energy ◽  
Water Waves ◽  
Wave Breaking ◽  
Surf Zone ◽  
Current System ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Conservation Of Energy ◽  
Wave Heating

This study investigates surf zone wave heating due to the dissipation of breaking wave energy by using the Smoothed Particle Hydrodynamics method. We evaluate the surf zone wave heating by examining the increase of internal energy of the system, which is computed based on the conservation of energy. The equivalent temperature profile is calculated based on a simple conversion relationship between energy and temperature. We first examine the surf zone wave heating based on long-crested wave breaking over a planar beach, and we consider spilling breaker and weakly plunging breaker. Numerical results show that breaking of water waves in the surf zone increases the internal energy of water body. Furthermore, the dissipation of incident wave energy is fully converted into the internal energy in a thermally isolated system, confirming the energy conservation of the present numerical approach. It is further found that the long-crested wave breaking generates undertow, which transports the generated wave heating from the surf zone to deep waters. We further carry out numerical experiments to examine surf zone wave heating due to short-crested wave breaking over a beach. The internal energy generation mainly follows the isolated wave breakers, and there is a 3D pattern of wave heating due to the complicated wave breaking process and current system. In general, the magnitude of the generated internal energy or temperature by dissipation of breaking wave energy in the surf zone is relatively small. The present study shows that the generated water temperature is in the order of 10^-3 Kelvin for wave breaking over a typical coastal beach.

scholarly journals Lagrangian Transport by Nonbreaking and Breaking Deep-Water Waves at the Ocean Surface

2019 ◽  
Vol 49 (4) ◽  
pp. 983-992 ◽  
Author(s):  
Nick Pizzo ◽  
W. Kendall Melville ◽  
Luc Deike
Keyword(s):  
Water Waves ◽  
Wave Breaking ◽  
Friction Velocity ◽  
Field Experiments ◽  
Breaking Waves ◽  
Stokes Drift ◽  
Breaking Wave ◽  
Significant Wave ◽  
Wind Speeds ◽  
Order Of Magnitude

AbstractUsing direct numerical simulations (DNS), Deike et al. found that the wave-breaking-induced mass transport, or drift, at the surface for a single breaking wave scales linearly with the slope of a focusing wave packet, and may be up to an order of magnitude larger than the prediction of the classical Stokes drift. This model for the drift due to an individual breaking wave, together with the statistics of wave breaking measured in the field, are used to compute the Lagrangian drift of breaking waves in the ocean. It is found that breaking may contribute up to an additional 30% to the predicted values of the classical Stokes drift of the wave field for the field experiments considered here, which have wind speeds ranging from 1.6 to 16 m s−1, significant wave heights in the range of 0.7–4.7 m, and wave ages (defined here as cm/u*, for the spectrally weighted phase velocity cm and the wind friction velocity u*) ranging from 16 to 150. The drift induced by wave breaking becomes increasingly more important with increasing wind friction velocity and increasing significant wave height.

PHYSICAL INTERPRETATION OF WAVE BREAKING CRITERIA

2017 ◽  
Author(s):  
Sergey Kuznetsov ◽  
Sergey Kuznetsov ◽  
Yana Saprykina ◽  
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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