Histograms, Cumulants, and Spectra of Mechanical and Wind Waves in a Wind-Wave Channel

The aim of the work is to obtain estimates and parameterization of the dissipation rate of the turbulence kinetic energy of (TKE-dissipation) in the upper water layer, induced by the presence of wind waves at the surface. For this purpose, data from the laboratory measurements of the wind waves and three components of currents at six horizons in the upper water layer and four different winds, performed in the wind-wave channel of IAP RAS [1, 2], were used. It was established that for a majority of horizons, the frequency spectra, SUz( f ), for the vertical component of the flow velocity, Uz, induced by wind and waves, have the Kolmogorov-type ranges of the kind: Using the algorithms described in [3, 4], this fact allows us to obtain estimates of the TKE-dissipation at the corresponding horizons, and then establish the dependence of on the friction velocity, u*, the height of waves at the surface, a0, the peak frequency of the spectrum, p, and the depth of the horizon, z. The analysis of the obtained results allows (for the available data) to propose a parameterization of the form 0.00025 for which a physical interpretation is proposed.

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EXPERIMENTAL STUDY OF WIND WAVES GENERATED ON CURRENTS

Coastal Engineering Proceedings ◽

10.9753/icce.v16.42 ◽

1978 ◽

Vol 1 (16) ◽

pp. 42

Author(s):

Hajime Kato ◽

Hiroichi Tsuruya

Keyword(s):

Wind Wave ◽

Wind Waves ◽

Water Current ◽

Pump System ◽

Frequency Wave ◽

Wave Channel ◽

Wave Heights ◽

Significant Wave Heights ◽

True Frequency ◽

The Waves

This paper presents some experimental results of wind waves generated on currents in a wind-wave channel with a water circulation pump system. The waves were measured at fetches less than 27.8 m by using resistance-type wave gauges. Surface velocities as well as velocity profiles in water were also measured elaborately and true frequency wave spectra were obtained from observed apparent spectra which were modified by the doppler effect of current. Significant wave heights Hwj computed from r)2 and peak frequencies of true spectra fprn were examined with emphasis. It was inferred from the variation of true spectra that the most prominent effect of water current is to change the effective fetch length. Then an idea of equivalent fetch length was proposed to express the current effect on the development of total wave energy. By using the equivalent fetch F' in place of the natural fetch it is shown that Hj/3 and fQm measured under various current conditions can be represented by the non-dimensional fetch relations, respectively, which were originally obtained in the case of no current.

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Whitecap coverage measurements in laboratory modeling of wind-wave interaction in presence of induced wave breaking

10.5194/egusphere-egu21-12033 ◽

2021 ◽

Author(s):

Alexander Kandaurov ◽

Yuliya Troitskaya ◽

Vasiliy Kazakov ◽

Daniil Sergeev

Keyword(s):

Wave Breaking ◽

Water Surface ◽

High Speed ◽

Wind Wave ◽

Wave Train ◽

Side Wall ◽

Channel Cross Section ◽

Whitecap Coverage ◽

Wave Channel ◽

Manual Processing

Whitecap coverage were retrieved from high-speed video recordings of the water surface obtained on the unique laboratory faculty The Large Thermostratified Test Tank with wind-wave channel (cross-section from 0.7&#215;0.7 to 0.7&#215;0.9 m2 at the end, 12 m fetch, wind velocity up to 35 m/s, U10 up to 65 m/s). The wind wave was induced using a wave generator installed at the beginning of the channel (a submerged horizontal plate, frequency 1.042 Hz, amplitude 93 mm) working in a pulsed operation (three periods). Wave breaking was induced in working area by a submerged plate (1.2&#215;0.7 m2, up to 12 depth, AOA -11,7&#176;). Experiments were carried out for equivalent wind velocities U10 from 17.8 to 40.1 m/s. Wire wave gauge was used to control the shape and phase of the incident wave.To obtain the surface area occupied by wave breaking, we used two Cygnet CY2MP-CL-SN cameras with 50 mm lenses. The cameras are installed above the channel at a height of 273 cm from the water surface, separated by 89 cm. The image scale was 302 &#956;m/px, the size of the image obtained from each camera is 2048x1088 px2, which corresponds to 619x328 mm2 (the long side of the frame along the channel). The shooting was carried out with a frequency of 50 Hz, an exposure time of 3 ms, 250 frames were recorded for each wave train. To illuminate the image areas to the side of the measurement area, a diffuse screen was placed on the side wall, which was illuminated by powerful LED lamps to create a uniform illumination source covering the entire side wall of the section.Using specially developed software for automatic detection of areas of wave breaking, the values of the whitecap coverage area were obtained. Automatic image processing was performed using morphological analysis in combination with manual processing of part of the frames for tweaking the algorithm parameters: for each mode, manual processing of several frames was performed, based on the results of which automatic algorithm parameters were selected to ensure that the resulting whitecap coverage corresponded. Comparison of images obtained from different angles made it possible to detect and exclude areas of glare on the surface from the whitecap coverage.The repeatability of the created wave breakings allows carrying out independent measurements for the same conditions, for example the parameters of spray generation will give estimations of the average number of fragmentation events per unit area of the wave breaking area.The work was supported by the RFBR grants 21-55-50005 and 20-05-00322 (conducting an experiment), President grant for young scientists &#1052;&#1050;-5503.2021.1.5 (software development) and the RSF grant No. 19-17-00209 (data processing).

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Loop-Type Wave-Generation Method for Generating Wind Waves under Long-Fetch Conditions

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-17-0043.1 ◽

2017 ◽

Vol 34 (10) ◽

pp. 2129-2139 ◽

Cited By ~ 6

Author(s):

Naohisa Takagaki ◽

Satoru Komori ◽

Mizuki Ishida ◽

Koji Iwano ◽

Ryoichi Kurose ◽

...

Keyword(s):

Wind Wave ◽

Wind Waves ◽

Peak Frequency ◽

Wave Generation ◽

New Wave ◽

Wave Tank ◽

Irregular Wave ◽

Wind Speeds ◽

Type Wave ◽

Wave Generator

AbstractIt is important to develop a wave-generation method for extending the fetch in laboratory experiments, because previous laboratory studies were limited to the fetch shorter than several dozen meters. A new wave-generation method is proposed for generating wind waves under long-fetch conditions in a wind-wave tank, using a programmable irregular-wave generator. This new method is named a loop-type wave-generation method (LTWGM), because the waves with wave characteristics close to the wind waves measured at the end of the tank are reproduced at the entrance of the tank by the programmable irregular-wave generator and the mechanical wave generation is repeated at the entrance in order to increase the fetch. Water-level fluctuation is measured at both normal and extremely high wind speeds using resistance-type wave gauges. The results show that, at both wind speeds, LTWGM can produce wind waves with long fetches exceeding the length of the wind-wave tank. It is observed that the spectrum of wind waves with a long fetch reproduced by a wave generator is consistent with that of pure wind-driven waves without a wave generator. The fetch laws between the significant wave height and the peak frequency are also confirmed for the wind waves under long-fetch conditions. This implies that the ideal wind waves under long-fetch conditions can be reproduced using LTWGM with the programmable irregular-wave generator.

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PROPAGATION OF WIND WAVES ON TIDES

Coastal Engineering Proceedings ◽

10.9753/icce.v21.36 ◽

1988 ◽

Vol 1 (21) ◽

pp. 36 ◽

Cited By ~ 1

Author(s):

Hendrick L. Tolman

Keyword(s):

Wave Propagation ◽

Wind Wave ◽

Numerical Models ◽

Wind Waves ◽

Absolute Frequency ◽

Shelf Seas ◽

Shelf Sea

Effects of instationary depths and currents in tides on shelf seas on wind wave propagation are investigated using two numerical models in two academical situations representing shelf sea conditions. It is shown that changes in absolute frequency, which are induced by the instationarity of depth and current, are significant in contrast to what is usually assumed. If these changes are neglected large and unpredictable errors may occur in calculated changes of wavenumber and amplitude.

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Miles Theory Revisited with Constant Vorticity in Water of Infinite Depth

Journal of Marine Science and Engineering ◽

10.3390/jmse8080623 ◽

2020 ◽

Vol 8 (8) ◽

pp. 623

Author(s):

Christian Kharif ◽

Malek Abid

Keyword(s):

Growth Rate ◽

Wave Energy ◽

Wind Wave ◽

Wind Waves ◽

Infinite Depth ◽

Energy Growth ◽

Constant Vorticity ◽

Generation Of Wind Waves ◽

Amplitude Growth

The generation of wind waves at the surface of a pre-existing underlying vertically sheared water flow of constant vorticity is considered. Emphasis is put on the role of the vorticity in water on wind-wave generation. The amplitude growth rate increases with the vorticity except for quite old waves. A limit to the wave energy growth is found in the case of negative vorticity, corresponding to the vanishing of the growth rate.

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On Evolution of Young Wind Waves in Time and Space

Atmosphere ◽

10.3390/atmos10090562 ◽

2019 ◽

Vol 10 (9) ◽

pp. 562 ◽

Cited By ~ 1

Author(s):

Shemer

Keyword(s):

Wave Field ◽

Field Experiments ◽

Wind Wave ◽

Wind Waves ◽

Wave Generation ◽

Wind Forcing ◽

Spatial And Temporal Variation ◽

Extensive Discussion ◽

Deterministic Theory ◽

Theoretical Approaches

The mechanisms governing the evolution of the wind-wave field in time and in space are not yet fully understood. Various theoretical approaches have been offered to model wind-wave generation. To examine their validity, detailed and accurate experiments under controlled conditions have to be carried out. Since it is next to impossible to get the required control of the governing parameters and to accumulate detailed data in field experiments, laboratory studies are needed. Extensive previously unavailable results on the spatial and temporal variation of wind waves accumulated in our laboratory under a variety of wind-forcing conditions and using diverse measuring techniques are reviewed. The spatial characteristics of the wind-wave field were determined using stereo video imaging. The turbulent airflow above wind waves was investigated using an X-hot film. The wave field under steady wind forcing as well as evolving from rest under impulsive loading was studied. An extensive discussion of the various aspects of wind waves is presented from a single consistent viewpoint. The advantages of the stochastic approach suggested by Phillips over the deterministic theory of wind-wave generation introduced by Miles are demonstrated. Essential differences between the spatial and the temporal analyses of wind waves’ evolution are discussed, leading to examination of the applicability of possible approaches to wind-wave modeling.

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Directional Analysis and Potential for Spectral Modelling of Infragravity Waves

Volume 7: Ocean Engineering ◽

10.1115/omae2016-54282 ◽

2016 ◽

Author(s):

Takehiko Nose ◽

Alexander Babanin ◽

Kevin Ewans

Keyword(s):

Wind Wave ◽

Wind Waves ◽

Field Research ◽

Army Corps ◽

Relative Depth ◽

Infragravity Waves ◽

Directional Information ◽

Us Army ◽

Dynamic Relationship ◽

Infragravity Wave

In this paper, we interrogated wave data collected by US Army Corps of Engineers at their well-known Field Research Facility, Duck, North Carolina and SHELL Corporation at Lagos, Nigeria. Both measurements were designed to collect wind waves with a conventional wave sampling configuration and not a dedicated infragravity wave sampling regime. Here, we developed a new approach to obtain directional information of and explored the potential to model infragravity waves in the spectral domain. It was found that infragravity wave heights had a strong dynamic relationship with an inverse relative depth parameter and that directional spreadings were moderately correlated with wind wave spreadings and wave energy. Further, infragravity directional spreadings were typically broader compared to their wind wave directional spreading counterparts.

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Wind Wave Growth at Short Fetch

Journal of Physical Oceanography ◽

10.1175/2007jpo3712.1 ◽

2008 ◽

Vol 38 (7) ◽

pp. 1597-1606 ◽

Cited By ~ 11

Author(s):

T. Lamont-Smith ◽

T. Waseda

Keyword(s):

Wind Speed ◽

Wave Height ◽

Significant Wave Height ◽

Field Data ◽

Wind Wave ◽

Wind Waves ◽

Retention Rates ◽

Horizontal Distance ◽

Wave Tank ◽

Significant Wave

Abstract Wave wire data from the large wind wave tank of the Ocean Engineering Laboratory at the University of California, Santa Barbara, are analyzed, and comparisons are made with published data collected in four other wave tanks. The behavior of wind waves at various fetches (7–80 m) is very similar to the behavior observed in the other tanks. When the nondimensional frequency F* or nondimensional significant wave height H* is plotted against nondimensional fetch x*, a large scatter in the data points is found. Multivariate regression to the dimensional parameters shows that significant wave height Hsig is a function of U2x and frequency F is a function of U1.25x, where U is the wind speed and x is the horizontal distance, with the result that in general for wind waves at a particular fetch in a wave tank, approximately speaking, the wave frequency is inversely proportional to the square root of the wind speed and the wavelength is proportional to the wind speed. Similarly, the wave height is proportional to U1.5 and the orbital velocity is proportional to U. Comparison with field data indicates a transition from this fetch law to the conventional one [the Joint North Sea Wave Project (JONSWAP)] for longer fetch. Despite differences in the fetch relationship for the wave tank and the field data, the wave height and wave period satisfy Toba’s 3/2 power law. This law imposes a strong constraint on the evolution of wind wave energy and frequency; consequently, the energy and momentum retention rate are not independent. Both retention rates grow with wind speed and fetch at the short fetches present in the wave tank. The observed retention rates are completely different from those typically observed in the field, but the same constraint (Toba’s 3/2 law) holds true.

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The Influence of Current on the Height of Wind Wave Run-Up: A comparison of experimental results with the Czech National Standard

Journal of Hydrology and Hydromechanics ◽

10.2478/v10098-012-0015-2 ◽

2012 ◽

Vol 60 (3) ◽

pp. 174-184 ◽

Cited By ~ 1

Author(s):

Jaromir Riha ◽

Miroslav Spano

Keyword(s):

Wind Wave ◽

Wind Waves ◽

Experimental Results ◽

National Standard ◽

Laboratory Research ◽

Left Bank ◽

Running Water ◽

Reliable Knowledge ◽

Run Up ◽

The Right

The Influence of Current on the Height of Wind Wave Run-Up: A comparison of experimental results with the Czech National StandardOne of the basic questions related to the safety of dikes and river levees is the size of the freeboard. One of the important parameters for freeboard design is the height of waves and wave run-up on levee slopes. Routine and standardised calculations of wave run-up deal with the freeboards of dams where wind waves originate on the still water of the reservoir. In the case of running water in streams (thereinafter only "currents") the effect of wave and current interaction on wave run-up is usually not taken into account due to the lack of reliable knowledge regarding the phenomenon. In the Czech Republic this question is topical in the case of large rivers such as the Elbe, the Vltava and the Morava. Within the framework of the projects Hydralab III and NAZV QI 92A139, hydraulic research and further analysis focused on wave run-up as a result of the combination of current and wind wave parameters were performed. The laboratory research was carried out in a hydraulic flume with a wavemaker on the right bank and a levee with a slope of 1:3 installed on the left bank opposite the wavemaker. Waves were generated both perpendicular and oblique to the levee axis; the angle of oblique wave attack varied within the range of ± 30°. The aim of this paper is to compare the results of the mentioned research with recommendations mentioned in the Czech National Standard CSN 75 0255Calculation of wave effects on water structuresand to quantify the effect of current on the wave run-up height.

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