On the two-dimensional structure of short gravity waves in a wind wave tank

Zavadsky, Andrey; Benetazzo, Alvise; Shemer, Lev

doi:10.1063/1.4973319

Cited by 41 publications

(43 citation statements)

References 59 publications

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“…However, reconstruction of the instantaneous water surface shape from stereo imaging is extremely computer-time consuming, somewhat limiting the number of imaged pairs of frames that can be processed for each wind-forcing condition and fetch in a reasonable time. More details on the stereo imaging technique applied in our experiments are given in [66].…”

Section: Experimental Facility and Techniquesmentioning

confidence: 99%

“…All experiments were controlled by a LabView program that enables running the experiment, including setting the wind speed in the tunnel, the vertical positioning of the air sensors, the calibration of the sensors before and after data acquisition sessions, and the data acquisition, in a fully automatic mode without human intervention. More information about the experimental facility, calibration of the sensors, and of the detailed experimental and data-processing procedures is provided in [51,63,66,67].…”

Section: Experimental Facility and Techniquesmentioning

confidence: 99%

“…Water velocity was measured at several fetches up to x = 410 cm from the entrance to the test section; at each fetch and wind velocity, about 350-400 were used. Special care was taken to provide adequate illumination; for details, see [66]. The 640 × 480-pixel camera imaged a 15-cm long area at the rate of 60 fps.…”

Section: Coupling Between Waves and Airflowmentioning

confidence: 99%

“…However, the wind-wave field is never unidirectional. The diverse approaches that have been applied in attempts to extract information on the two-dimensional structure of the wave field were briefly reviewed in [66]. To this end, two essentially different methods described in Section 2 were used in our studies to gain information on the 2D spatial structure of wind waves: stereo video imaging and the laser slope gauge (LSG).…”

Section: The Two-dimensional Features Of the Wind-wave Fieldmentioning

confidence: 99%

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On Evolution of Young Wind Waves in Time and Space

Shemer

2019

Atmosphere

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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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Section: Experimental Facility and Techniquesmentioning

confidence: 99%

Section: Experimental Facility and Techniquesmentioning

confidence: 99%

Section: Coupling Between Waves and Airflowmentioning

confidence: 99%

Section: The Two-dimensional Features Of the Wind-wave Fieldmentioning

confidence: 99%

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On Evolution of Young Wind Waves in Time and Space

Shemer

2019

Atmosphere

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“…The friction velocity at the air-water interface determined by two independent methods was shown to be a function solely of wind forcing and practically independent of fetch. Ebuchi, Kawamura & Toba (1987), Caulliez & Collard (1999), Zavadsky, Benetazzo & Shemer (2017) and emphasized the three-dimensional structure of the wind-wave field and studied its spatial evolution.…”

Section: Introductionmentioning

confidence: 99%

Water waves excited by near-impulsive wind forcing

Zavadsky

Shemer

2017

J. Fluid Mech.

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Only limited information is currently available on the evolution of waves generated by wind that varies in time, and in particular on the initial stages of wind-wave growth from rest under a suddenly applied wind forcing. The emerging wind-wave field varies in time as well as in space. Detailed knowledge of wave parameter distributions under those conditions contributes to a better understanding of the mechanisms of wind wave generation. In the present study, the instantaneous surface elevation and two components of the instantaneous surface slope were recorded at various fetches in a small-scale experimental facility under nearly impulsive wind forcing. Numerous independent realizations have been recorded for each selection of operational conditions. Sufficient data at a number of fetches were accumulated to calculate reliable ensemble-averaged statistical parameters of the evolving random wind-wave field as a function of the time elapsed from activation of wind forcing. Distinct stages in the wave evolution process from appearance of initial ripples to emergence of a quasi-steady wind-wave field were identified. The experimental results during each stage of evolution were analysed in view of the viscous instability theory by Kawai (J.

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Scanning stereo-PLIF method for free surface measurements in large 3D domains

2020

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In this work, we extend a planar laser-induced fluorescence method for free surface measurements to a three-dimensional domain using a stereo-camera system, a scanning light sheet, and a modified self-calibration procedure. The stereo-camera setup enables a versatile measurement domain with self-calibration, improved accuracy, and redundancy (e.g., possibility to overcome occlusions). Fluid properties are not significantly altered by the fluorescent dye, which results in a non-intrusive measurement technique. The technique is validated by determining the free surface of a hydraulic flow over an obstacle and circular waves generated after droplet impact. Free surface waves can be accurately determined over a height of L = 100 mm in a large two-dimensional domain (y(x, z) = 120 × 62 mm 2), with sufficient accuracy to determine small amplitude variations (≈ 0.2 mm). The temporal resolution (t = 19 ms) is only limited by the available scanning equipment (f = 1 kHz rate). For other applications, this domain can be scaled as needed.

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On the two-dimensional structure of short gravity waves in a wind wave tank

Cited by 41 publications

References 59 publications

On Evolution of Young Wind Waves in Time and Space

On Evolution of Young Wind Waves in Time and Space

Water waves excited by near-impulsive wind forcing

Scanning stereo-PLIF method for free surface measurements in large 3D domains

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