scholarly journals Miles Theory Revisited with Constant Vorticity in Water of Infinite Depth

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.

Influence of following, regular and irregular long waves on wind-wave growth with fetch: an experimental study

2021 ◽  
Author(s):  
Antoine Villefer ◽  
Michel Benoit ◽  
Damien Violeau ◽  
Christopher Luneau ◽  
Hubert Branger
Keyword(s):  
Wave Energy ◽  
Wind Wave ◽  
Wind Waves ◽  
Peak Frequency ◽  
Long Waves ◽  
Specific Method ◽  
Wave Growth ◽  
Wind Velocities ◽  
Series Of Experiments ◽  
Frequency Variations

AbstractA series of experiments were conducted in a wind-wave tank facility in Marseilles (France) to study the effects of preexisting swell conditions (represented by long mechanically-generated waves) on wind-wave growth with fetch. Both monochromatic and irregular (JONSWAP-type) long wave conditions with different values of wave steepness have been generated in the presence of a constant wind forcing, for several wind velocities. A spectral analysis of temporal wave signals combined with airflow measurements allowed to study the evolution of both wave systems with the aim of identifying the interaction mechanisms transportable to prototype scale. In particular, a specific method is used to separate the two wave systems in the measured bimodal spectra. In fetch-limited conditions, pure wind-wave growth is in accordance with anterior experiments, but differs from the prototype scale in terms of energy and frequency variations with fetch. Monochromatic long waves are shown to reduce the energy of the wind-waves significantly, as it was observed in anterior laboratory experiments. The addition of JONSWAP-type long waves instead results in a downshift of the wind-wave peak frequency but no significant energy reduction. Overall, it is observed that the presence of long waves affects the wind-wave energy and frequency variations with fetch. Finally, in the presence of JONSWAP-type long waves, variations of wind-wave energy and peak frequency with fetch appear in close agreement with the wind-wave growth observed at prototype scale both in terms of variations and nondimensional magnitude.

Wind-induced growth of water waves

1982 ◽  
Vol 123 ◽  
pp. 425-442 ◽  
Author(s):  
H. Mitsuyasu ◽  
T. Honda
Keyword(s):  
Growth Rate ◽  
Water Waves ◽  
Friction Velocity ◽  
Wind Wave ◽  
Wind Waves ◽  
Pure Water ◽  
Wave Flume ◽  
Wind Speeds ◽  
Wind Profiles ◽  
The Waves

Spatial growth of mechanically generated water waves under the action of wind has been measured in a laboratory wind-wave flume both for pure water and for water containing a surfactant (sodium lauryl sulphate, concentration 2.6 × 10−2%). I n the latter case, no wind waves develop on the surface of the mechanically generated waves as well as on the still water surface for wind speeds up to U10≈ 15 m/s, where U10 is the wind velocity at the height Z = 10 m. Therefore we can study the wind-induced growth of monochromatic waves without the effects of co-existing short wind waves. The mechanically generated waves grew exponentially under the action of the wind, with fetch in both cases. The measured growth rate β for the pure water can be fitted by β/f = 0.34(U*/C)2 0.1 [lsime ] U*/C [lsime ] 1.0, where f is the frequency of the waves, C is the corresponding phase velocity, and U, is the friction velocity obtained from vertical wind profiles. The effect of the wave steepness H/L on the dimensionless growth rate β/f is not clear, but seems to be small. For water containing the surfactant, the measured growth rate is smaller than that for pure water, but the friction velocity of the wind is also small, and the above relation between β/f and U*/C holds approximately if the measured friction velocity U* is used for the relation.

scholarly journals WAVE HEIGHT DISTRIBUTION OF WIND WAVES OVER LONG WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 21
Author(s):  
Shan-Hwei Ou ◽  
Frederick L.W. Tang
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Wind Wave ◽  
Wind Waves ◽  
Rayleigh Distribution ◽  
Long Waves ◽  
Height Distribution ◽  
Long Wave ◽  
Wave Height Distribution ◽  
Wave Generator

Influence of long wave on the wave height distribution of wind waves was studied through the laboratory experiment. Experiments were conducted in a wind-wave tank where the wind waves were generated by a wind blower and the long waves were developed by an oscillating pendulum type wave generator. The wave height distribution of the wind waves over long wave is slightly different from the Rayleigh distribution in the small steepness of long wave. The ratios between the average of highest l/n-th waves vary with the steepness of long waves. The magnitude and the location of the spectral peak of wind waves are altered. The amount of the attenuation of wind wave energy is larger than the results of Mitsuyasu (1966).

scholarly journals The contribution of wind-wave energy at sea bottom to the modelling of rhodolith beds distribution in an off-shore continental shelf

2020 ◽  
Author(s):  
SABRINA AGNESI ◽  
ALDO ANNUNZIATELLIS ◽  
ROBERTO INGHILESI ◽  
GIULIA MΟ ◽  
ARIANNA ORASI
Keyword(s):  
Wave Energy ◽  
Wind Wave ◽  
Wind Waves ◽  
Surface Wind ◽  
Western Mediterranean ◽  
Benthic Habitat ◽  
North West ◽  
Western Mediterranean Sea ◽  
Sea Bottom ◽  
The Relationship

The study aims to investigate the relationship between the presence of rhodolith beds and the effect on the shelf bottom boundary layer due to the action of surface wind waves. The study area is situated off-shore and north-west of Elba Island in the Western Mediterranean Sea, an area known to be characterized by rhodolith beds. A binomial logistic regression model is used in order to analyse the relationship between wind-wave energy at sea bottom, bathymetry and rhodolith bed occurrence. The results indicate a positive correlation between rhodolith bed occurrence and wave energy, while the relation with bathymetry is weaker in all the trials. The wave energy confidence interval associated to the rhodolith bed probability is also estimated, thereby informing on wind wave energy values required for the modelling of this particular benthic habitat in off-shore shelf areas.

scholarly journals Predicting Wind Wave Suppression on Irregular Long Waves

2020 ◽  
Vol 8 (8) ◽  
pp. 619
Author(s):  
Taylor Bailey ◽  
Lauren Ross ◽  
Mary Bryant ◽  
Duncan Bryant
Keyword(s):  
Growth Rate ◽  
Wind Wave ◽  
Wind Waves ◽  
Irregular Waves ◽  
Single Wave ◽  
Irregular Wave ◽  
Induced Stress ◽  
Wide Range ◽  
Wave Induced ◽  
Monochromatic Waves

The applicability of the wind wave suppression model developed by Chen and Belcher (2000) to irregular wave environments is investigated in this study. Monochromatic and irregular wave environments were simulated in the W2 (Wind/Wave) laboratory at the University of Maine under varying wind speeds. The Chen and Belcher (2000) model accurately predicts the reduction of the energy density of the wind waves in the presence of the monochromatic waves as a function of wave steepness, but under predicts this energy dissipation for the irregular waves. This is due to the consideration of a single wave frequency in the estimation of the growth rate and wave-induced stress of the monochromatic waves. The same formulations for the growth rate and wave-induced stress cannot be applied to irregular waves because their spectra contain energy over a wide range of frequencies. A revised version of the model is proposed to account for the energy contained within multiple wave frequencies from the power spectra for the mechanically generated irregular waves. The revised model shows improved results when applied to irregular wave environments.

On weakly turbulent scaling of wind sea in simulations of fetch-limited growth

2011 ◽  
Vol 669 ◽  
pp. 178-213 ◽  
Author(s):  
ELODIE GAGNAIRE-RENOU ◽  
MICHEL BENOIT ◽  
SERGEI I. BADULIN
Keyword(s):  
Numerical Simulations ◽  
Wave Energy ◽  
Water Waves ◽  
Wind Wave ◽  
Wind Waves ◽  
Initial Growth ◽  
Limited Growth ◽  
Wave Growth ◽  
Wide Range ◽  
Wind Sea

Extensive numerical simulations of fetch-limited growth of wind-driven waves are analysed within two approaches: a ‘traditional’ wind-speed scaling first proposed by Kitaigorodskii (Bull. Acad. Sci. USSR, Geophys. Ser., Engl. Transl., vol. N1, 1962, p. 105) in the early 1960s and an alternative weakly turbulent scaling developed recently by Badulin et al. (J. Fluid Mech.591, 2007, 339–378). The latter one uses spectral fluxes of wave energy, momentum and action as physical scales of the problem and allows for advanced qualitative and quantitative analysis of wind-wave growth and features of air–sea interaction. In contrast, the traditional approach is shown to be descriptive rather than proactive. Numerical simulations are conducted on the basis of the Hasselmann kinetic equation for deep-water waves in a wide range of wind speeds from 5 to 30 m s −1 and for the ideal case of fetch-limited growth: permanent wind blowing perpendicularly to a straight coastline. Two different wave input functions, Sin, and two methods for calculating the nonlinear transfer term Snl (Gaussian quadrature method, or GQM, a quasi-exact method based on the use of Gaussian quadratures, and the discrete interaction approximation, or DIA) are used in the simulations. Comparison of the corresponding results firstly shows the relevance of the analysis of wind-wave growth in terms of the proposed weakly turbulent scaling, and secondly, allows us to highlight some critical points in the modelling of wind-generated waves. Three stages of wind-wave development corresponding to qualitatively different balance of the source terms, Sin, Sdiss and Snl, are identified: initial growth, growing sea and fully developed sea. Validity of the asymptotic weakly turbulent approach for the stage of growing wind sea is determined by the dominance of nonlinear transfers, which results in a rigid link between spectral fluxes and wave energy. This stage of self-similar growth is investigated in detail and presented as a consequence of three sub-stages of qualitatively different coupling of air flow and growing wind waves. The key self-similarity parameter of the asymptotic theory is estimated to be αss = 0.68 ± 0.1.Further prospects of wind-wave modelling in the context of the presented weakly turbulent scaling are discussed.

The growth of duration-limited wind waves

1978 ◽  
Vol 85 (4) ◽  
pp. 705-730 ◽  
Author(s):  
Hisashi Mitsuyasu ◽  
Kunio Rikiishi
Keyword(s):  
Growth Rate ◽  
Exponential Growth ◽  
Empirical Formula ◽  
Wind Wave ◽  
Wind Waves ◽  
Wave Spectrum ◽  
Peak Frequency ◽  
Spectral Peak ◽  
Spectral Energy ◽  
Wave Spectra

Laboratory measurements have been made of the one-dimensional spectra of the duration-limited wind waves which are generated when a wind abruptly begins to blow over a water surface, maintaining a constant speed during the succeeding period of time. The duration dependences of the wave energy E and the spectral peak frequency fm determined from the measured spectra are slightly different from those inferred from the fetch dependences of these quantities. The normalized spectra of the duration-limited wind waves are also slightly different from those of fetch-limited wind waves: the concentration of the normalized spectral energy near the spectral peak frequency is smaller, in many cases, for the duration-limited wind waves than for fetch-limited wind waves. The exponential growth rates β of the duration-limited wind-wave spectra are generally larger than those of fetch-limited wind-wave spectra. Furthermore, both for the duration-limited wind waves and for fetch-limited wind waves the exponential growth rate has a behaviour which is different from the empirical formula of Snyder & Cox (1966). A new empirical formula for the growth rate of the wave spectrum is proposed, from which the empirical formula of Snyder & Cox (1966) can be derived as a special case. Agreement between the new empirical formula and the experimental results is satisfactory for fetch-limited wave spectra, but is confined to the qualitative features for the duration-limited wave spectra.

Generation of Wind Waves in Large Streams

2020 ◽  
Vol 24 (1) ◽  
pp. 518-525
Author(s):  
Eshev S.S.– DSc ◽  
I.X. Gayimnazarov ◽  
А.R. Rakhimov ◽  
Latipov Sh. A
Keyword(s):  
Wind Waves ◽  
Generation Of Wind Waves

Emerging Challenges and Opportunities of Mobile Commerce in India: A Study on Societal Perspective

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Utkarsh Kumar ◽  
Anil Kumar Gope ◽  
Shweta Singh
Keyword(s):  
Growth Rate ◽  
Societal Perspective ◽  
Mobile Applications ◽  
Mobile Application ◽  
Mobile Commerce ◽  
Mobile Banking ◽  
Black And White ◽  
The People ◽  
Challenges And Opportunities

In India, the position of mobile banking was in saga and this time, it is in pic position. The speedof reaching the people is going high and high. This is time of wireless world and sense of prestige; no doubt the mobile commerce is contributing to enhance the beauty of life and playing the role of metaphor and has become the part and parcel of our life. This growth has changed people to do business in mobile commerce (М- Commerce). Peoples are transferring to M-Commerce to attain good and fast transaction into market and saving their precious time. M-Commerce has become distinguished in Indian people, quickly during last few years. Due to large number of mobile application, growth rate in mobile penetration in India is increasing with the rapid speed. The mobile users has shifted to use the android phone from simple and black and white phone and taking the service of internet, the role of telecom companies is also important in the being popular of mobile commerce. Although many people have started E-Commerce but still a separate part of the society feel uncomfortable and hesitate to use M-Commerce because of security problems, payment issues and complexity of mobile applications. This paper identifies facts about the feasibility of MCommercein India today its growth and the Strength and opportunity, weakness and threats lying ahead.

Sign in / Sign up

Export Citation Format

Share Document