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Articoli di riviste sul tema "Wind-waves"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 luglio 2024

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1

S.S.– DSc, Eshev, I. X. Gayimnazarov, А. R. Rakhimov e Latipov Sh. A. "Generation of Wind Waves in Large Streams". International Journal of Psychosocial Rehabilitation 24, n. 1 (31 gennaio 2020): 518–25. http://dx.doi.org/10.37200/ijpr/v24i1/pr200157.

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2

Ryan, Marleigh Grayer, Yasushi Inoue e James T. Araki. "Wind and Waves". World Literature Today 63, n. 3 (1989): 537. http://dx.doi.org/10.2307/40145521.

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3

Ogborn, Miles. "Wind and Waves". Slavery & Abolition 41, n. 3 (23 giugno 2020): 669–76. http://dx.doi.org/10.1080/0144039x.2020.1784662.

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4

Kuznetsova, A., G. Baydakov, A. Dosaev, D. Sergeev e Yu Troitskaya. "Wind Waves Modeling Under Hurricane Wind Conditions". Journal of Physics: Conference Series 1163 (febbraio 2019): 012054. http://dx.doi.org/10.1088/1742-6596/1163/1/012054.

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5

Frigaard, Peter. "Wind generated ocean waves". Coastal Engineering 42, n. 1 (gennaio 2001): 103. http://dx.doi.org/10.1016/s0378-3839(00)00061-2.

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6

Wiegel, R. L. "WIND WAVES AND SWELL". Coastal Engineering Proceedings 1, n. 7 (29 gennaio 2011): 1. http://dx.doi.org/10.9753/icce.v7.1.

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Winds blowing over the water surface generate waves. In general the higher the wind velocity, the larger the fetch over which it blows, and the longer it blows the higher and longer will be the average waves . Waves still under the action of the winds that created them are called wind waves, or a sea. They are forced waves rather than free waves. They are variable in their direction of advance (Arthur, 1949). They are irregular in the direction of propagation. The flow is rotational due to the shear stress of the wind on the water surface and it is quite turbulent as observations of dye in the water indicates. After the waves leave the generating area their characteristics become somewhat different, principally they are smoother, losing the rough appearance due to the disappearance of the multitude of smaller waves on top of the bigger ones and the whitecaps and spray. When running free of the storm the waves are known as swell. In Fig. 1 are shown some photographs taken in the laboratory of waves still rising under the action of wind and this same wave system after it has left the windy section of the wind-wave tunnel. It can be seen thati-the freely running swell has a smoother appearance than the waves in the windy section. The motion of the swell is nearly irrotational and nonturbulent, unless the swell runs into other regions where the water is in turbulent motion. Turbulence is a property of the fluid rather than of the wave motion. After the waves have travelled a distance from the generating area they have lost some energy due to air resistance, internal friction, and by large scale turbulent scattering if they run into other storm areas, and the rest of the energy has become spread over a larger area due to the dispersive and angular spreading characteristics of water gravity waves. All of these mechanisms lead to a decrease in energy density. Thus, the waves become lower in height. In addition, due to their dispersive characteristic the component wave periods tend to segregate in such a way that the longest waves lead the main body of waves and the shortest waves form the tail of the main body of waves. Finally, the swell may travel through areas where winds are present, adding new wind waves to old swell, and perhaps directly increasing or decreasing the size of the old swell.

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7

Havas, Magda, e David Colling. "Wind Turbines Make Waves". Bulletin of Science, Technology & Society 31, n. 5 (30 settembre 2011): 414–26. http://dx.doi.org/10.1177/0270467611417852.

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8

Gough, Douglas. "Waves in the wind". Nature 376, n. 6536 (luglio 1995): 120–21. http://dx.doi.org/10.1038/376120a0.

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9

Huttunen, K. E. J., S. D. Bale, T. D. Phan, M. Davis e J. T. Gosling. "Wind/WAVES observations of high-frequency plasma waves in solar wind reconnection exhausts". Journal of Geophysical Research: Space Physics 112, A1 (gennaio 2007): n/a. http://dx.doi.org/10.1029/2006ja011836.

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10

Naeser, Harald. "The Capillary Waves’ Contribution to Wind-Wave Generation". Fluids 7, n. 2 (10 febbraio 2022): 73. http://dx.doi.org/10.3390/fluids7020073.

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Published theories and observations have shown that dissipation of gravity waves implies frequency downshifting of wave energy. Hence, for wind-waves, the wind energy input to the highest frequencies is of special interest. Here it is shown that this input is vital, because the direct wind energy input obtained by the air-pressure’s work on most gravity waves is slightly less than what the waves need to grow. Further, the wind’s input of the angular momentum that waves need to grow is found to be absent at most gravity wave frequencies. The capillary waves that appear at the surface of the sea when the wind is blowing solve these problems. To demonstrate this, an extension of linear wave theory is established to study possibilities and limitations for transfer of energy and angular momentum from the wind to waves through these frequencies. The theory describes regular, gravity–capillary waves with constant amplitude under laminar conditions. It includes surface tensions, viscosity, gravity and a wind-generated shear current, and shows that these waves—contrary to most gravity waves—receive more energy from the wind than they dissipate and angular momentum they cannot keep. Hence, the problem of the missing input of energy and angular momentum from wind to gravity waves is solved by transfers through the capillary waves. This implies that capillary waves are vital to obtain growing gravity waves.

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11

Liu, Huiqing, Lian Xie, Leonard J. Pietrafesa e Shaowu Bao. "Sensitivity of wind waves to hurricane wind characteristics". Ocean Modelling 18, n. 1 (gennaio 2007): 37–52. http://dx.doi.org/10.1016/j.ocemod.2007.03.004.

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12

Husain, Nyla T., Tetsu Hara e Peter P. Sullivan. "Wind Turbulence over Misaligned Surface Waves and Air–Sea Momentum Flux. Part I: Waves Following and Opposing Wind". Journal of Physical Oceanography 52, n. 1 (gennaio 2022): 119–39. http://dx.doi.org/10.1175/jpo-d-21-0043.1.

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Abstract Air–sea momentum and scalar fluxes are strongly influenced by the coupling dynamics between turbulent winds and a spectrum of waves. Because direct field observations are difficult, particularly in high winds, many modeling and laboratory studies have aimed to elucidate the impacts of the sea state and other surface wave features on momentum and energy fluxes between wind and waves as well as on the mean wind profile and drag coefficient. Opposing wind is common under transient winds, for example, under tropical cyclones, but few studies have examined its impacts on air–sea fluxes. In this study, we employ a large-eddy simulation for wind blowing over steep sinusoidal waves of varying phase speeds, both following and opposing wind, to investigate impacts on the mean wind profile, drag coefficient, and wave growth/decay rates. The airflow dynamics and impacts rapidly change as the wave age increases for waves following wind. However, there is a rather smooth transition from the slowest waves following wind to the fastest waves opposing wind, with gradual enhancement of a flow perturbation identified by a strong vorticity layer detached from the crest despite the absence of apparent airflow separation. The vorticity layer appears to increase the effective surface roughness and wave form drag (wave attenuation rate) substantially for faster waves opposing wind. Significance Statement Surface waves increase friction at the sea surface and modify how wind forces upper-ocean currents and turbulence. Therefore, it is important to include effects of different wave conditions in weather and climate forecasts. We aim to inform more accurate forecasts by investigating wind blowing over waves propagating in the opposite direction using large-eddy simulation. We find that when waves oppose wind, they decay as expected, but also increase the surface friction much more drastically than when waves follow wind. This finding has important implications for how waves opposing wind are represented as a source of surface friction in forecast models.

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13

Chen, Gang, e Stephen E. Belcher. "Effects of Long Waves on Wind-Generated Waves". Journal of Physical Oceanography 30, n. 9 (settembre 2000): 2246–56. http://dx.doi.org/10.1175/1520-0485(2000)030<2246:eolwow>2.0.co;2.

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14

Takagaki, Naohisa, Naoya Suzuki, Yuliya Troitskaya, Chiaki Tanaka, Alexander Kandaurov e Maxim Vdovin. "Effects of current on wind waves in strong winds". Ocean Science 16, n. 5 (10 settembre 2020): 1033–45. http://dx.doi.org/10.5194/os-16-1033-2020.

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Abstract. It is important to investigate the effects of current on wind waves, called the Doppler shift, at both normal and extremely high wind speeds. Three different types of wind-wave tanks along with a fan and pump are used to demonstrate wind waves and currents in laboratories at Kyoto University, Japan, Kindai University, Japan, and the Institute of Applied Physics, Russian Academy of Sciences, Russia. Profiles of the wind and current velocities and the water-level fluctuation are measured. The wave frequency, wavelength, and phase velocity of the significant waves are calculated, and the water velocities at the water surface and in the bulk of the water are also estimated by the current distribution. The study investigated 27 cases with measurements of winds, waves, and currents at wind speeds ranging from 7 to 67 m s−1. At normal wind speeds under 30 m s−1, wave frequency, wavelength, and phase velocity depend on wind speed and fetch. The effect of the Doppler shift is confirmed at normal wind speeds; i.e., the significant waves are accelerated by the surface current. The phase velocity can be represented as the sum of the surface current and artificial phase velocity, which is estimated by the dispersion relation of the deepwater waves. At extremely high wind speeds over 30 m s−1, a similar Doppler shift is observed as under the conditions of normal wind speeds. This suggests that the Doppler shift is an adequate model for representing the acceleration of wind waves by current, not only for wind waves at normal wind speeds but also for those with intensive breaking at extremely high wind speeds. A weakly nonlinear model of surface waves at a shear flow is developed. It is shown that it describes dispersion properties well not only for small-amplitude waves but also strongly nonlinear and even breaking waves, which are typical for extreme wind conditions (over 30 m s−1).

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15

Rodriguez Gandara, Ruben, e John Harris. "NEARSHORE WAVE DAMPING DUE TO THE EFFECT ON WINDS IN RESPONSE TO OFFSHORE WIND FARMS". Coastal Engineering Proceedings 1, n. 33 (25 ottobre 2012): 55. http://dx.doi.org/10.9753/icce.v33.waves.55.

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Despite the progress that has been made in modeling wind wake interaction between turbines in offshore wind farms, only a handful of studies have quantified the impact of wind turbines or wave farms upon surface waves, and there are even less articles about the wave blockage induced by the whole array of turbines upon wind waves. This hypothetical case study proposes a methodology that takes into account the combined effect of wind wake and wave blockage on wind waves when transforming offshore waves to nearshore in an offshore wind farm scenario.

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16

Starodubtsev, Sergei, Anton Zverev, Peter Gololobov e Vladislav Grigoryev. "Cosmic ray fluctuations and MHD waves in the solar wind". Solar-Terrestrial Physics 9, n. 2 (29 giugno 2023): 73–80. http://dx.doi.org/10.12737/stp-92202309.

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During large-scale solar wind disturbances, variations in galactic cosmic rays with periods from several minutes to 2–3 hours, which are called cosmic ray fluctuations in the scientific literature, often occur. Such fluctuations are not observed in the absence of disturbances. Since cosmic rays are charged particles, their modulation in the heliosphere occurs mainly under the influence of the interplanetary magnetic field, or rather its turbulent part — MHD waves. In order to adequately describe the relationship between their fluctuation spectra, it is necessary to be able to isolate a certain type of MHD waves from direct measurements of the interplanetary medium parameters. In this paper, we consider some methods for determining the contribution of three solar wind MHD turbulence branches, namely, Alfvén, fast, and slow magnetosonic waves corresponding to the turbulence spectrum inertial region frequencies 10⁻⁴<ν<10⁻¹ Hz, at which cosmic ray fluctuations are observed, to the observed power spectra of interplanetary magnetic field modulus fluctuations. To do this, we apply the methods of spectral and polarization analysis. In the absence of measurement data on SW parameters, to identify the type of MHD turbulence we use the known wave polarization properties that Alfvén and magnetosonic waves are polarized in different planes relative to the plane containing the average IMF vector and wave vector. Our results show that with the correct determination of the spectra of three MHD wave types, their sum, within the limits of errors, agrees well with the observed spectra of the interplanetary magnetic field modulus, and a small difference can be attributed to static inhomogeneities and oscillations frozen into plasma, as well as to various discontinuities that are always inevitably present in the solar wind.

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17

Contardo, Stephanie, Graham Symonds, Laura Segura, Ryan Lowe e Jeff Hansen. "Infragravity Wave Energy Partitioning in the Surf Zone in Response to Wind-Sea and Swell Forcing". Journal of Marine Science and Engineering 7, n. 11 (28 ottobre 2019): 383. http://dx.doi.org/10.3390/jmse7110383.

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An alongshore array of pressure sensors and a cross-shore array of current velocity and pressure sensors were deployed on a barred beach in southwestern Australia to estimate the relative response of edge waves and leaky waves to variable incident wind wave conditions. The strong sea breeze cycle at the study site (wind speeds frequently > 10 m s−1) produced diurnal variations in the peak frequency of the incident waves, with wind sea conditions (periods 2 to 8 s) dominating during the peak of the sea breeze and swell (periods 8 to 20 s) dominating during times of low wind. We observed that edge wave modes and their frequency distribution varied with the frequency of the short-wave forcing (swell or wind-sea) and edge waves were more energetic than leaky waves for the duration of the 10-day experiment. While the total infragravity energy in the surf zone was higher during swell forcing, edge waves were more energetic during wind-sea periods. However, low-frequency (0.005–0.023 Hz) edge waves were found to be dominant in absence of wind-sea conditions, while higher-frequency (0.023–0.050 Hz) edge waves dominated when wind-sea conditions were present.

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18

Takagaki, Naohisa, Satoru Komori, Mizuki Ishida, Koji Iwano, Ryoichi Kurose e Naoya Suzuki. "Loop-Type Wave-Generation Method for Generating Wind Waves under Long-Fetch Conditions". Journal of Atmospheric and Oceanic Technology 34, n. 10 (ottobre 2017): 2129–39. http://dx.doi.org/10.1175/jtech-d-17-0043.1.

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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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19

Van Vledder, G. Ph, e L. H. Holthuijsen. "WAVES IN TURNING WIND FIELDS". Coastal Engineering Proceedings 1, n. 21 (29 gennaio 1988): 43. http://dx.doi.org/10.9753/icce.v21.43.

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A numerical model to compute to a high degree of accuracy nonlinear wave-wave interactions of wind generated waves supplemented with formulations of wind generation and white-capping, has been used to estimate qualitatively and quantitatively the effect of these physical processes on the directional response of waves in a turning wind field. After a sudden shift in wind direction the wave spectrum develops a secondary peak in the new wind direction. The initial peak of the spectrum either merges fairly quickly with this new peak or it slowly disappears, depending on the magnitude of the directional wind shift. The turning of the mean wave direction towards the new wind direction is caused by wind generation. The processes of nonlinear wave-wave interactions and white-capping tend to slow down the turning rate induced by the wind generation. The net turning rate of the mean wave direction in the model is twice as slow as in observations acquired in the central and southern North Sea.

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20

Greenslade, Diana, Mark Hemer, Alex Babanin, Ryan Lowe, Ian Turner, Hannah Power, Ian Young et al. "Priorities for Wind-Waves Research". Bulletin of the American Meteorological Society 101, n. 6 (giugno 2020): 505–7. http://dx.doi.org/10.1175/bams-d-18-0262.a.

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21

Donelan, M. A., M. Curcic, S. S. Chen e A. K. Magnusson. "Modeling waves and wind stress". Journal of Geophysical Research: Oceans 117, n. C11 (17 luglio 2012): n/a. http://dx.doi.org/10.1029/2011jc007787.

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22

Hemer, Mark A., Xiaolan L. Wang, Ralf Weisse e Val R. Swail. "Advancing Wind-Waves Climate Science". Bulletin of the American Meteorological Society 93, n. 6 (giugno 2012): 791–96. http://dx.doi.org/10.1175/bams-d-11-00184.1.

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23

Komen, Gerbrand. "Interactions of wind and waves". Nature 328, n. 6130 (agosto 1987): 480. http://dx.doi.org/10.1038/328480a0.

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24

Cavaleri, Luigi, e Stefano Zecchetto. "Reynolds stresses under wind waves". Journal of Geophysical Research 92, n. C4 (1987): 3894. http://dx.doi.org/10.1029/jc092ic04p03894.

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25

Nevins, A., e R. E. Yahnke. "Whisper, The Waves, The Wind". Gerontologist 27, n. 4 (1 agosto 1987): 533–34. http://dx.doi.org/10.1093/geront/27.4.533.

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26

Rao, A. D., e J. W. de Vries. "Wind waves: modeling and observations". Natural Hazards 49, n. 2 (9 gennaio 2009): 163–64. http://dx.doi.org/10.1007/s11069-008-9338-z.

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27

Jia, Pan, Bruno Andreotti e Philippe Claudin. "Paper waves in the wind". Physics of Fluids 27, n. 10 (ottobre 2015): 104101. http://dx.doi.org/10.1063/1.4931777.

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28

Jahoda, Karel, e Tamara Spanila. "On Motion of Wind Waves". Water Resources 31, n. 3 (maggio 2004): 266–70. http://dx.doi.org/10.1023/b:ware.0000028696.13749.f5.

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29

Xu, Delun, Paul A. Hwang e Jin Wu. "Breaking of Wind-Generated Waves". Journal of Physical Oceanography 16, n. 12 (dicembre 1986): 2172–78. http://dx.doi.org/10.1175/1520-0485(1986)016<2172:bowgw>2.0.co;2.

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30

Banner, Michael L. "Equilibrium Spectra of Wind Waves". Journal of Physical Oceanography 20, n. 7 (luglio 1990): 966–84. http://dx.doi.org/10.1175/1520-0485(1990)020<0966:esoww>2.0.co;2.

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31

Maat, N., C. Kraan e W. A. Oost. "The roughness of wind waves". Boundary-Layer Meteorology 54, n. 1-2 (gennaio 1991): 89–103. http://dx.doi.org/10.1007/bf00119414.

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32

Husain, Nyla T., Tetsu Hara e Peter P. Sullivan. "Wind Turbulence over Misaligned Surface Waves and Air–Sea Momentum Flux. Part II: Waves in Oblique Wind". Journal of Physical Oceanography 52, n. 1 (gennaio 2022): 141–59. http://dx.doi.org/10.1175/jpo-d-21-0044.1.

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Abstract The coupled dynamics of turbulent airflow and a spectrum of waves are known to modify air–sea momentum and scalar fluxes. Waves traveling at oblique angles to the wind are common in the open ocean, and their effects may be especially relevant when constraining fluxes in storm and tropical cyclone conditions. In this study, we employ large-eddy simulation for airflow over steep, strongly forced waves following and opposing oblique wind to elucidate its impacts on the wind speed magnitude and direction, drag coefficient, and wave growth/decay rate. We find that oblique wind maintains a signature of airflow separation while introducing a cross-wave component strongly modified by the waves. The directions of mean wind speed and mean wind shear vary significantly with height and are misaligned from the wind stress direction, particularly toward the surface. As the oblique angle increases, the wave form drag remains positive, but the wave impact on the equivalent surface roughness (drag coefficient) rapidly decreases and becomes negative at large angles. Our findings have significant implications for how the sea-state-dependent drag coefficient is parameterized in forecast models. Our results also suggest that wind speed and wind stress measurements performed on a wave-following platform can be strongly contaminated by the platform motion if the instrument is inside the wave boundary layer of dominant waves. Significance Statement Surface waves increase friction at the sea surface and modify how wind forces upper-ocean currents and turbulence. Therefore, it is important to include effects of different wave conditions in weather and climate forecasts. We aim to inform more accurate forecasts by investigating wind blowing over waves propagating in oblique directions using large-eddy simulation. We find that waves traveling at a 45° angle or larger to the wind grow as expected, but do not increase or even decrease the surface friction felt by the wind—a surprising result that has significant implications for how oblique wind-waves are represented as a source of surface friction in forecast models.

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33

van der Werf, Ivo, e Marcel van Gent. "Wave Overtopping over Coastal Structures with Oblique Wind and Swell Waves". Journal of Marine Science and Engineering 6, n. 4 (6 dicembre 2018): 149. http://dx.doi.org/10.3390/jmse6040149.

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Most guidelines on wave overtopping over coastal structures are based on conditions with waves from one direction only. Here, wave basin tests with oblique wave attack are presented where waves from one direction are combined with waves from another direction. This is especially important for locations where wind waves approach a coastal structure under a specific direction while swell waves approach the coastal structure under another direction. The tested structure was a dike with a smooth and impermeable 1:4 slope. The test programme consisted of four types of wave loading: (1) Wind waves only: “sea” (approaching the structure with an angle of 45°), (2) Wind waves and swell waves from the same direction (45°), (3) Wind waves and swell waves, simultaneously from two different directions (45° and −45°, thus perpendicular to each other), and (4) Wind waves, simultaneously from two different directions (45° and −45°, thus perpendicular to each other). Existing guidelines on wave overtopping have been extended to predict wave overtopping discharges under the mentioned types of wave loading (oblique sea and swell conditions).

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Draxl, Caroline, Rochelle P. Worsnop, Geng Xia, Yelena Pichugina, Duli Chand, Julie K. Lundquist, Justin Sharp, Garrett Wedam, James M. Wilczak e Larry K. Berg. "Mountain waves can impact wind power generation". Wind Energy Science 6, n. 1 (7 gennaio 2021): 45–60. http://dx.doi.org/10.5194/wes-6-45-2021.

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Abstract. Mountains can modify the weather downstream of the terrain. In particular, when stably stratified air ascends a mountain barrier, buoyancy perturbations develop. These perturbations can trigger mountain waves downstream of the mountains that can reach deep into the atmospheric boundary layer where wind turbines operate. Several such cases of mountain waves occurred during the Second Wind Forecast Improvement Project (WFIP2) in the Columbia River basin in the lee of the Cascade Range bounding the states of Washington and Oregon in the Pacific Northwest of the United States. Signals from the mountain waves appear in boundary layer sodar and lidar observations as well as in nacelle wind speeds and power observations from wind plants. Weather Research and Forecasting (WRF) model simulations also produce mountain waves and are compared to satellite, lidar, and sodar observations. Simulated mountain wave wavelengths and wave propagation speeds (group velocities) are analyzed using the fast Fourier transform. We found that not all mountain waves exhibit the same speed and conclude that the speed of propagation, magnitudes of wind speeds, or wavelengths are important parameters for forecasters to recognize the risk for mountain waves and associated large drops or surges in power. When analyzing wind farm power output and nacelle wind speeds, we found that even small oscillations in wind speed caused by mountain waves can induce oscillations between full-rated power of a wind farm and half of the power output, depending on the position of the mountain wave's crests and troughs. For the wind plant analyzed in this paper, mountain-wave-induced fluctuations translate to approximately 11 % of the total wind farm output being influenced by mountain waves. Oscillations in measured wind speeds agree well with WRF simulations in timing and magnitude. We conclude that mountain waves can impact wind turbine and wind farm power output and, therefore, should be considered in complex terrain when designing, building, and forecasting for wind farms.

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Sakhnenko, O. I. "Results of calculation of wave-wind water dynamics at the Tiligul Estuary". Ukrainian hydrometeorological journal, n. 18 (29 ottobre 2017): 140–49. http://dx.doi.org/10.31481/uhmj.18.2016.16.

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Features of spatial distribution of the main parameters of wind waves, such as height, average orbital velocities of wave motions determining transportation of bottom material were specified. Maximum heights of significant waves were obtained in the central, most deep-water part of the estuary, as well as in the southern part and near the windward shores. At the time of storm winds maximum heights of significant waves, according to the simulation results, constitute up to 0,83 m. On the basis of calculations of wind waves with application of the SWAN numerical model (Simulating Waves Nearshore) made using wind observations during 2012, regime functions of wind waves’ heights for different parts of the estuary were built. Statistical estimates of wind waves’ heights at typical points of the estuary waters were analyzed. Spatial fields of wind-wave flows in the estuary under the influence of steady winds of the southern and western directions calculated using the complex of numerical mathematical models of wind wave generation and models of wind-wave water circulation based on Reynolds equations and supplemented with com-ponents of the wave radiation stresses were specified.

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36

Chen, Shi-Ming. "Water Exchange Due to Wind and Waves in a Monsoon Prevailing Tropical Atoll". Journal of Marine Science and Engineering 11, n. 1 (5 gennaio 2023): 109. http://dx.doi.org/10.3390/jmse11010109.

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Physical forcings affect water exchange in coral reef atolls. Characteristics of the consequent water exchange depend on the atoll morphology and the local atmospheric and hydrographic conditions. The pattern of water exchange at the Dongsha atoll under the influences of tides, wind, and waves was investigated by conducting realistic modeling and numerical experiments. The analyses suggest that the southwestern wind could enhance the inflow transports at the southern reef flat and the outflow transports at the northern reef flat/north channel. The northeastern wind induces an inversed pattern. Unlike the wind, the waves always strengthen the inflow transports at the reef flat, and the locations of strengthened transports depend on the incident directions of the waves. Wind and waves induce shorter hydrodynamic time scales than tides, suggesting more vigorous water exchange during high wind and waves. The directions of wind and waves significantly affect the spatial distributions of the residence time and the age. This implies that the hydrodynamic processes in the Dongsha Atoll would have significant seasonal variability. This study presents different circulation patterns in an atoll system influenced by calm weather and strong wind/waves.

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37

Lee, J. H., e J. P. Monty. "On the Interaction between Wind Stress and Waves: Wave Growth and Statistical Properties of Large Waves". Journal of Physical Oceanography 50, n. 2 (febbraio 2020): 383–97. http://dx.doi.org/10.1175/jpo-d-19-0112.1.

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AbstractStatistical properties and development of wave fields with different wind forcings are investigated through parametric laboratory experiments. Thirty different, random sea states simulated using a JONSWAP spectrum are mechanically generated in deep-water conditions. Each of the random simulated sea states is exactly repeated but subjected to a range of different wind speeds to study the interaction between wind stress and the existing random sea state waves, especially the isolated effect of the wind stress on the largest waves. Wave crest distributions are sensitive to the wind at the extreme end such that there is an observed deviation from second-order theory for the largest (lowest probability) waves at high wind speed. Because the local wave steepness increases with wind speed, eventually reaching a breaking point, the growth of extreme waves (relative to the significant wave height) due to wind stress is shown to be limited by wave breaking. Even when large waves are breaking, the data reveal that amplitude modulation of wave groups is enhanced substantially as the wind speed increases due to the difference in growth rates between the highest and the lowest wave crests in a wave group. However, there is no evidence of an increase in modulation instability with the wind speed, suggesting that the wind–wave interaction under strong wind forcing dominates the wave growth mechanism over nonlinear wave interactions in a broadband wave field.

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38

Zavolgensky, M. V., e P. B. Rutkevich. "Turbulent wind waves on a water current". Advances in Geosciences 15 (13 maggio 2008): 35–45. http://dx.doi.org/10.5194/adgeo-15-35-2008.

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Abstract. An analytical model of water waves generated by the wind over the water surface is presented. A simple modeling method of wind waves is described based on waves lengths diagram, azimuthal hodograph of waves velocities and others. Properties of the generated waves are described. The wave length and wave velocity are obtained as functions on azimuth of wave propagation and growth rate. Motionless waves dynamically trapped into the general picture of three dimensional waves are described. The gravitation force does not enter the three dimensional of turbulent wind waves. That is why these waves have turbulent and not gravitational nature. The Langmuir stripes are naturally modeled and existence of the rogue waves is theoretically proved.

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39

Morland, L. C. "Oblique wind waves generated by the instability of wind blowing over water". Journal of Fluid Mechanics 316 (10 giugno 1996): 163–72. http://dx.doi.org/10.1017/s0022112096000481.

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The growth rates of gravity waves are computed from linear, inviscid stability theory for wind velocity profiles that are representative of the mean flow in a turbulent boundary layer. The energy transfer to the waves is largely concentrated in an angle (to the wind) interval that broadens with increasing wind speed and narrows with increasing wavelength. At sufficiently high wind speeds and sufficiently short wavelengths, the waves of maximum growth rate propagate at an oblique angle to the wind. The connection with bimodal directional distributions of observed spectra is discussed.

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40

Makin, V. K., H. Branger, W. L. Peirson e J. P. Giovanangeli. "Stress above Wind-Plus-Paddle Waves: Modeling of a Laboratory Experiment". Journal of Physical Oceanography 37, n. 12 (1 dicembre 2007): 2824–37. http://dx.doi.org/10.1175/2007jpo3550.1.

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Abstract A model based on wind-over-waves coupling (WOWC) theory is used to simulate a laboratory experiment and to explain the observed peculiarities of the surface stress distribution above a combined wave field: wind-generated-plus-monochromatic-paddle waves. Observations show the systematic and significant decrease in the stress as the paddle wave is introduced into the pure wind-wave field. As the paddle-wave steepness is further increased, the stress level returns to the stress level characteristic of the pure wind waves. Further increase in the paddle-wave steepness augments the stress further. The WOWC model explains this peculiarity of the stress distribution by the fact that the paddle waves significantly damp the wind waves in the spectral peak. The stress supported by these dominant waves rapidly falls when the paddle wave is introduced, and this decrease is not compensated by the stress induced by the paddle wave. With further increase in the steepness of the paddle wave, the stress supported by dominant wind waves stays at a low level while the stress supported by the paddle waves continues to grow proportional to the square of the steepness, finally exceeding the stress level characteristic of the pure wind-wave field.

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41

GOTO, CHIAKI. "Relation between wind and wind waves of Osaka Bay." PROCEEDINGS OF COASTAL ENGINEERING, JSCE 36 (1989): 168–72. http://dx.doi.org/10.2208/proce1989.36.168.

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42

Kukulka, Tobias, e Tetsu Hara. "The Effect of Breaking Waves on a Coupled Model of Wind and Ocean Surface Waves. Part II: Growing Seas". Journal of Physical Oceanography 38, n. 10 (1 ottobre 2008): 2164–84. http://dx.doi.org/10.1175/2008jpo3962.1.

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Abstract This is the second part of a two-part investigation of a coupled wind and wave model that includes the enhanced form drag of breaking waves. The model is based on the wave energy balance and the conservation of air-side momentum and energy. In Part I, coupled nonlinear advance–delay differential equations were derived, which govern the wave height spectrum, the distribution of breaking waves, and vertical air side profiles of the turbulent stress and wind speed. Numeric solutions were determined for mature seas. Here, numeric solutions for a wide range of wind and wave conditions are obtained, including young, strongly forced wind waves. Furthermore, the “spatial sheltering effect” is introduced so that smaller waves in airflow separation regions of breaking longer waves cannot be forced by the wind. The solutions strongly depend on the wave height curvature spectrum at high wavenumbers (the “threshold saturation level”). As the threshold saturation level is reduced, the effect of breaking waves becomes stronger. For young strongly forced waves (laboratory conditions), breaking waves close to the spectral peak dominate the wind input and previous solutions of a model with only input to breaking waves are recovered. Model results of the normalized roughness length are generally consistent with previous laboratory and field measurements. For field conditions, the wind stress depends sensitively on the wave height spectrum. The spatial sheltering may modify the number of breaking shorter waves, in particular, for younger seas.

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43

Henney, William J., e S. J. Arthur. "Bow shocks, bow waves, and dust waves – III. Diagnostics". Monthly Notices of the Royal Astronomical Society 489, n. 2 (16 agosto 2019): 2142–58. http://dx.doi.org/10.1093/mnras/stz2283.

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ABSTRACT Stellar bow shocks, bow waves, and dust waves all result from the action of a star’s wind and radiation pressure on a stream of dusty plasma that flows past it. The dust in these bows emits prominently at mid-infrared wavelengths in the range 8 to 60 $\mu$m. We propose a novel diagnostic method, the τ–η diagram, for analysing these bows, which is based on comparing the fractions of stellar radiative energy and stellar radiative momentum that is trapped by the bow shell. This diagram allows the discrimination of wind-supported bow shocks, radiation-supported bow waves, and dust waves in which grains decouple from the gas. For the wind-supported bow shocks, it allows the stellar wind mass-loss rate to be determined. We critically compare our method with a previous method that has been proposed for determining wind mass-loss rates from bow shock observations. This comparison points to ways in which both methods can be improved and suggests a downward revision by a factor of two with respect to previously reported mass-loss rates. From a sample of 23 mid-infrared bow-shaped sources, we identify at least four strong candidates for radiation-supported bow waves, which need to be confirmed by more detailed studies, but no strong candidates for dust waves.

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44

Alielden, Khaled, e Youra Taroyan. "Evolution of Alfvén Waves in the Solar Wind. Monochromatic Driver". Astrophysical Journal 935, n. 2 (1 agosto 2022): 66. http://dx.doi.org/10.3847/1538-4357/ac7f41.

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Abstract We use a 2.5D magnetohydrodynamic model to investigate the propagation of azimuthally driven Alfvén waves with different periods and their interaction with the solar wind. In the absence of waves, the dipole field is stretched into a helmet streamer by the solar wind. The wind speeds near the equator are lower than those in the mid and high latitudes. Magnetic reconnection in the equatorial plasma sheet regularly triggers a breakup and expulsion of a plasmoid. We next inject monochromatic Alfvén waves with a moderate amplitude of 9 km s−1 and a period of τ = 1000 s at the coronal base. A cavity showing features of forward and backward propagating modes is formed. The backward waves are able to accelerate the background plasma at mid and high latitudes through the nonlinear coupling to compressional waves. The size of the cavity increases with the period of the Alfvén waves as long as the outer boundary remains in the sub-Alfvénic wind. When τ = 4000 s, we find enhanced acceleration and heating of the solar wind plasma as well as suppression of the reconnection in the equatorial plasma sheet. The amplitudes of the backward Alfvén waves remain large inside the cavity and modify its size. The cavity ceases to exist as its outer boundary gradually moves into the super-Alfvénic wind and the large amplitude backward waves are swept away by the wind. Results suggest that Alfvén waves with moderate amplitudes can modify the dynamics and the energetics of the solar wind plasma with the embedded magnetic field.

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45

PHILLIPS, W. R. C. "Langmuir circulations beneath growing or decaying surface waves". Journal of Fluid Mechanics 469 (15 ottobre 2002): 317–42. http://dx.doi.org/10.1017/s0022112002001908.

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The instability to longitudinal vortices of two-dimensional density-stratified temporally evolving wavy shear flow is considered. The problem is posited in the context of Langmuir circulations, LCs, beneath wind-driven surface waves and the instability mechanism is generalized Craik–Leibovich, either CLg or CL2. Of interest is the influence of non-stationary base flows on the instability according to linear theory. It is found that the instability is described by a family of similarity solutions and that the growth rate of the instability, in non-stationary base flows, is doubly exponential in time, although the growth rate reduces to exponential when the base flow is stationary. An example is given for weakly sheared wind-driven flow evolving in the presence of growing irrotational surface waves. Waves aligned both with the wind and counter to it are considered, as is the role of stratification. Antecedent to the example is an initial value problem posed by Leibovich & Paolucci (1981) for neutral waves in slowly evolving shear. Here, however, the waves and shear may grow (or decay) at rates comparable with the LCs. Furthermore the current here has two components: a wind-driven portion due to the wind stress applied at the free surface and a second due to the diffusion of momentum due to the wave-amplitude-squared free-surface stress condition. Using the case for neutral waves in non-stratified uniform shear for reference, it is found, in general, that growing waves are stabilizing while decaying waves are destabilizing to the formation of LCs, although the latter applies only for sufficiently large spanwise spacings and is subject to a globally stable lower bound. Decaying waves in the absence of wind can also be destabilizing to LCs. When the wind is counter to the waves, however, only decaying waves are unstable to LCs. Furthermore, while growing waves are stable to the formation of LCs in the presence of stable stratification, decaying waves are unstable in both aligned and opposed wind-wave conditions. Unstable stratification on the other hand, is destabilizing to LCs for all temporal waves in both aligned and opposed wind-wave conditions.

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46

Shen, Wei, e Klaus-Werner Gurgel. "Wind Direction Inversion from Narrow-Beam HF Radar Backscatter Signals in Low and High Wind Conditions at Different Radar Frequencies". Remote Sensing 10, n. 9 (16 settembre 2018): 1480. http://dx.doi.org/10.3390/rs10091480.

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Land-based, high-frequency (HF) surface wave radar has the unique capability of monitoring coastal surface parameters, such as current, waves, and wind, up to 200 km off the coast. The Doppler spectrum of the backscattered radar signal is characterized by two strong peaks that are caused by the Bragg-resonant scattering from the ocean surface. The wavelength of Bragg resonant waves is exactly half the radio wavelength (grazing incidence), and these waves are located at the higher frequency part of the wave spectral distribution. When HF radar operates at higher frequencies, the resonant waves are relatively shorter waves, which are more sensitive to a change in wind direction, and they rapidly respond to local wind excitation and a change in wind direction. When the radar operates at lower frequencies, the corresponding resonant waves are relatively longer and take longer time to respond to a change in wind direction due to the progress of wave growth from short waves to long waves. For the wind inversion from HF radar backscatter signals, the accuracy of wind measurement is also relevant to radar frequency. In this paper, a pattern-fitting method for extracting wind direction by estimating the wave spreading parameter is presented, and a comparison of the pattern-fitting method and a conventional method is given as well, which concludes that the pattern-fitting method presents better results than the conventional method. In order to analyze the wind direction inversion from radar backscatter signals under different wind conditions and at different radar frequencies, two radar experiments accomplished in Norway and Italy are introduced, and the results of wind direction inversion are presented. In the two experiments, the radar worked at 27.68 MHz and 12 MHz, respectively, and the wind conditions at the sea surface were quite different. In the experiment in Norway, 67.4% of the wind records were higher than 5 m/s, while, in the experiment in Italy, only 18.9% of the wind records were higher than 5 m/s. All these factors affect the accuracy of wind direction inversion. The paper analyzes the radar data and draws a conclusion on the influencing factor of wind direction inversion.

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47

Banner, Michael L. "The influence of wave breaking on the surface pressure distribution in wind—wave interactions". Journal of Fluid Mechanics 211 (febbraio 1990): 463–95. http://dx.doi.org/10.1017/s0022112090001653.

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In reviewing the current status of our understanding of the mechanisms underlying wind-wave generation, it is apparent that existing theories and models are not applicable to situations where the sea surface is disturbed by breaking waves, and that the available experimental data on this question are sparse. In this context, this paper presents the results of a detailed study of the effects of wave breaking on the aerodynamic surface pressure distribution and consequent wave-coherent momentum flux, as well as its influence on the total wind stress.Two complementary experimental configurations were used to focus on the details and consequences of the pressure distribution over breaking waves under wind forcing. The first utilized a stationary breaking wave configuration and confirmed the presence of significant phase shifting, due to air flow separation effects, between the surface pressure and surface elevation (and slope) distributions over a range of wind speeds. The second configuration examined the pressure distribution, recorded at a fixed height above the mean water surface just above the crest level, over short mechanically triggered waves which were induced to break almost continuously under wind forcing. This allowed a very detailed comparison of the form drag for actively breaking waves and for waves of comparable steepness just prior to breaking (‘incipiently’ breaking waves). For these propagating steep-wave experiments, the pressure phase shifts and distributions closely paralleled the stationary configuration findings. Moreover, a large increase (typically 100%) in the total windstress was observed for the breaking waves, with the increase corresponding closely to the comparably enhanced form drag associated with the actively breaking waves.In addition to further elucidating some fundamental features of wind-wave interactions for very steep wind waves, this paper provides a useful data set for future model calculations of wind flow over breaking waves. The results also provide the basis for a parameterization of the wind input source function applicable for a wave field undergoing active breaking, an important result for numerical modelling of short wind waves.

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48

Neumann, Gerhard. "NOTES ON THE GENERATION AND GROWTH OF OCEAN WAVES UNDER WIND ACTION". Coastal Engineering Proceedings 1, n. 3 (1 gennaio 2000): 7. http://dx.doi.org/10.9753/icce.v3.7.

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Abstract (sommario):

The basic problem of forecasting wind-generated waves is the development of equations which express the energy budget between wind and waves, and the derivation of physical laws governing the growth of the component wave trains. The waves can grow only in the case where the supply of energy by wind exceeds the loss of energy by friction and turbulence. Thus any attempt to calculate the growth of ocean waves under wind action requires a knowledge of the energy supply and the energy dissipation in every phase of wave development.

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49

Kahma, Kimmo K., Mark A. Donelan, William M. Drennan e Eugene A. Terray. "Evidence of Energy and Momentum Flux from Swell to Wind". Journal of Physical Oceanography 46, n. 7 (luglio 2016): 2143–56. http://dx.doi.org/10.1175/jpo-d-15-0213.1.

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AbstractMeasurements of pressure near the surface in conditions of wind sea and swell are reported. Swell, or waves that overrun the wind, produces an upward flux of energy and momentum from waves to the wind and corresponding attenuation of the swell waves. The estimates of growth of wind sea are consistent with existing parameterizations. The attenuation of swell in the field is considerably smaller than existing measurements in the laboratory.

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50

Miller, Sarah J., Omar H. Shemdin e Michael S. Longuet-Higgins. "Laboratory measurements of modulation of short-wave slopes by long surface waves". Journal of Fluid Mechanics 233 (dicembre 1991): 389–404. http://dx.doi.org/10.1017/s0022112091000538.

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Hydrodynamic modulation of wind waves by long surface waves in a wave tank is investigated, at wind speeds ranging from 1.5 to 10 m s−1. The results are compared with the linear, non-dissipative, theory of Longuet-Higgins & Stewart (1960), which describes the modulation of a group of short gravity waves due to straining of the surface by currents produced by the orbital motions of the long wave, and work done against the radiation stresses of the short waves. In most cases the theory is in good agreement with the experimental results when the short waves are not too steep, and the rate of growth due to the wind is relatively small. At the higher wind speeds, the effects of wind-wave growth, dissipation and wave-wave interactions are dominant.

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