scholarly journals Searching for chaotic deterministic features in laboratory water surface waves

2000 ◽  
Vol 7 (1/2) ◽  
pp. 37-48 ◽  
Author(s):  
M. Joelson ◽  
Th. Dudok de Wit ◽  
Ph. Dussouillez ◽  
A. Ramamonjiarisoa
Keyword(s):  
Surface Waves ◽  
Water Surface ◽  
Wind Waves ◽  
Theoretical Models ◽  
Resonant Interactions ◽  
Mechanical Waves ◽  
Random Character ◽  
Nonlinear Features ◽  
Low Dimensional ◽  
Laboratory Water

Abstract. The dynamic evolution of laboratory water surface waves has been studied within the framework of dynamical systems with the aim to identify stochastic or deterministic nonlinear features. Three different regimes are considered: pure wind waves, pure mechanical waves and mixed (wind and mechanical) waves. These three regimes show different dynamics. The results on wind waves do not clearly support the recently proposed idea that a deterministic Stokes-like component dominate the evolution of such waves; they are more appropriately described by a similarity-like approach that includes a random character. Cubic resonant interactions are clearly identified in pure mechanical waves using tricoherence functions. However, detailed aspects of the interactions do not fully agree with existing theoretical models. Finally, a deterministic motion is observed in mixed waves, which therefore are best described by a low dimensional nonlinear deterministic process.

Experimental study of the initial stages of wind waves' spatial evolution

2011 ◽  
Vol 681 ◽  
pp. 462-498 ◽  
Author(s):  
DAN LIBERZON ◽  
LEV SHEMER
Keyword(s):  
Energy Transfer ◽  
Growth Rates ◽  
Water Surface ◽  
Wind Waves ◽  
Pressure Fluctuations ◽  
Theoretical Models ◽  
Small Scale ◽  
Wave Flume ◽  
Spatial Growth ◽  
The Mean

Despite a significant progress and numerous publications over the last few decades a comprehensive understanding of the process of waves' excitation by wind still has not been achieved. The main goal of the present work was to provide as comprehensive as possible set of experimental data that can be quantitatively compared with theoretical models. Measurements at various air flow rates and at numerous fetches were carried out in a small scale, closed-loop, 5 m long wind wave flume. Mean airflow velocity and fluctuations of the static pressure were measured at 38 vertical locations above the mean water surface simultaneously with determination of instantaneous water surface elevations by wave gauges. Instantaneous fluctuations of two velocity components were recorded for all vertical locations at a single fetch. The water surface drift velocity was determined by the particle tracking velocimetry (PTV) method. Evaluation of spatial growth rates of waves at various frequencies was performed using wave gauge records at various fetches. Phase relations between various signals were established by cross-spectral analysis. Waves' celerities and pressure fluctuation phase lags relative to the surface elevation were determined. Pressure values at the water surface were determined by extrapolating the measured vertical profile of pressure fluctuations to the mean water level and used to calculate the form drag and consequently the energy transfer rates from wind to waves. Directly obtained spatial growth rates were compared with those obtained from energy transfer calculations, as well as with previously available data.

Laboratory investigation of the effect of sea foam on the scattering of microwave radiation

2020 ◽  
Author(s):  
Georgy Baydakov ◽  
Ermakova Olga ◽  
Vdovin Maxim ◽  
Sergeev Daniil ◽  
Troitskaya Yuliya
Keyword(s):  
Wind Speed ◽  
Surface Waves ◽  
Water Surface ◽  
Wind Waves ◽  
Short Wave ◽  
Doppler Spectrum ◽  
Momentum Exchange ◽  
High Frequency Region ◽  
Wave Flume ◽  
The Impact

<p>This paper models the impact of the presence of foam on the short-wave component of surface waves and momentum exchange in the atmospheric boundary layer at high winds. First, physical experiments were carried out in a wind-wave flume in which foam can be artificially produced at the water surface. Tests were conducted under high wind-speed conditions where equivalent 10-m wind speed, U10, ranged 12–38 m/s, with measurements made of the airflow parameters, the frequency-wavenumber spectra of the surface waves, the foam coverage of the water surface, and the distribution of the foam bubbles.</p><p>Microwave measurements were performed using a coherent Doppler X-band scatterometer with a wavelength of 3.2 cm and a sequential reception of linearly polarized radiation. It was shown that the presence of foam reduces the NRCS of the agitated water surface. Foam formations are concentrated mainly on the ridges and front slopes of wind waves, which make the main contribution to the scattering of radio waves. This may explain the effect of reducing the total NRCS: foam, which has less reflective properties, masks the main diffusers on the water surface. The second mechanism is associated with the effect of foam on short waves, by analogy with surfactant films.</p><p>The effect of foam on the shape of the Doppler spectrum of a microwave signal scattered by the water surface was investigated. In the case of weak wind, the presence of foam on the surface leads to a decrease in the short-wave part of the spectrum of surface waves and, as a result, to a decrease in the scattered signal. In addition, a mirror component appears in the Doppler spectrum corresponding to the fundamental frequency of the wave. In the case of a stronger wind, the grouping of additional scatterers (foam) on the crests of the waves leads to a shift of the Doppler spectra to the high-frequency region.</p><p>The work was supported by the RFBR (grants 18-35-20068, 19-05-00366, 19-05-00249) and the RF President’s Grant for Young Scientists (MK-144.2019.5).</p>

scholarly journals Localization of water surface waves in a heterostructure channel with corrugated sidewalls

AIP Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 015336
Author(s):  
Jia-Yi Zhang ◽  
Ting Liu ◽  
Jia Tao ◽  
Ya-Xian Fan ◽  
Zhi-Yong Tao
Keyword(s):  
Surface Waves ◽  
Water Surface

scholarly journals Suppression of Wind Ripples and Microwave Backscattering Due to Turbulence Generated by Breaking Surface Waves

2020 ◽  
Vol 12 (21) ◽  
pp. 3618
Author(s):  
Stanislav Ermakov ◽  
Vladimir Dobrokhotov ◽  
Irina Sergievskaya ◽  
Ivan Kapustin
Keyword(s):  
Remote Sensing ◽  
Surface Waves ◽  
Wave Breaking ◽  
Wave Train ◽  
Wind Waves ◽  
Breaking Waves ◽  
Doppler Spectrum ◽  
Strong Wave ◽  
Wave Maker ◽  
Radar Backscattering

The role of wave breaking in microwave backscattering from the sea surface is a problem of great importance for the development of theories and methods on ocean remote sensing, in particular for oil spill remote sensing. Recently it has been shown that microwave radar return is determined by both Bragg and non-Bragg (non-polarized) scattering mechanisms and some evidence has been given that the latter is associated with wave breaking, in particular, with strong breaking such as spilling or plunging. However, our understanding of mechanisms of the action of strong wave breaking on small-scale wind waves (ripples) and thus on the radar return is still insufficient. In this paper an effect of suppression of radar backscattering after strong wave breaking has been revealed experimentally and has been attributed to the wind ripple suppression due to turbulence generated by strong wave breaking. The experiments were carried out in a wind wave tank where a frequency modulated wave train of intense meter-decimeter-scale surface waves was generated by a mechanical wave maker. The wave train was compressed according to the gravity wave dispersion relation (“dispersive focusing”) into a short-wave packet at a given distance from the wave maker. Strong wave breaking with wave crest overturning (spilling) occurred for one or two highest waves in the packet. Short decimeter-centimeter-scale wind waves were generated at gentle winds, simultaneously with the long breaking waves. A Ka-band scatterometer was used to study microwave backscattering from the surface waves in the tank. The scatterometer looking at the area of wave breaking was mounted over the tank at a height of about 1 m above the mean water level, the incidence angle of the microwave radiation was about 50 degrees. It has been obtained that the radar return in the presence of short wind waves is characterized by the radar Doppler spectrum with a peak roughly centered in the vicinity of Bragg wave frequencies. The radar return was strongly enhanced in a wide frequency range of the radar Doppler spectrum when a packet of long breaking waves arrived at the area irradiated by the radar. After the passage of breaking waves, the radar return strongly dropped and then slowly recovered to the initial level. Measurements of velocities in the upper water layer have confirmed that the attenuation of radar backscattering after wave breaking is due to suppression of short wind waves by turbulence generated in the breaking zone. A physical analysis of the effect has been presented.

Action of an adverse current on the shape of deep water surface waves

1995 ◽  
Vol 18 (6) ◽  
pp. 438-444 ◽  
Author(s):  
P. Bonmarin ◽  
F. Bartholin ◽  
A. Ramamonjiarisoa
Keyword(s):  
Surface Waves ◽  
Deep Water ◽  
Water Surface

Image sequence analysis of water surface waves in a hydraulic wind wave tank

1999 ◽  
Author(s):  
Christian M. Senet ◽  
Nicole Braun ◽  
Philipp A. Lange ◽  
Joerg Seemann ◽  
Heiko Dankert ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Surface Waves ◽  
Water Surface ◽  
Wind Wave ◽  
Image Sequence ◽  
Image Sequence Analysis ◽  
Wave Tank

scholarly journals Numerical Evidence of Turbulence Generated by Nonbreaking Surface Waves

2015 ◽  
Vol 45 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Wu-ting Tsai ◽  
Shi-ming Chen ◽  
Guan-hung Lu
Keyword(s):  
Surface Waves ◽  
Water Surface ◽  
Nonlinear Boundary Conditions ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Langmuir Turbulence ◽  
Near Surface ◽  
Order Of Magnitude ◽  
Turbulence Production ◽  
Wave Induced

AbstractNumerical simulation of monochromatic surface waves propagating over a turbulent field is conducted to reveal the mechanism of turbulence production by nonbreaking waves. The numerical model solves the primitive equations subject to the fully nonlinear boundary conditions on the exact water surface. The result predicts growth rates of turbulent kinetic energy consistent with previous measurements and modeling. It also validates the observed horizontal anisotropy of the near-surface turbulence that the spanwise turbulent intensity exceeds the streamwise component. Such a flow structure is found to be attributed to the formation of streamwise vortices near the water surface, which also induces elongated surface streaks. The averaged spacing between the streaks and the depth of the vortical cells approximates that of Langmuir turbulence. The strength of the vortices arising from the wave–turbulence interaction, however, is one order of magnitude less than that of Langmuir cells, which arises from the interaction between the surface waves and the turbulent shear flow. In contrast to Langmuir turbulence, production from the Stokes shear does not dominate the energetics budget in wave-induced turbulence. The dominant production is the advection of turbulence by the velocity straining of waves.

Resonant Interactions and Chaotic Excitation in Nonlinear Surface Waves in Dense Plasma

2021 ◽  
pp. 1-12
Author(s):  
Amit Ghosh ◽  
Jyotirmoy Goswami ◽  
Swarniv Chandra ◽  
Chinmay Das ◽  
Yash Arya ◽  
...  
Keyword(s):  
Surface Waves ◽  
Dense Plasma ◽  
Resonant Interactions ◽  
Nonlinear Surface Waves ◽  
Nonlinear Surface
Sign in / Sign up

Export Citation Format

Share Document