scholarly journals UPWIND TRAVEL OF REFLECTED WAVES

1968 ◽  
Vol 1 (11) ◽  
pp. 14
Author(s):  
E.P. Richey
Keyword(s):  
Wind Waves ◽  
Full Scale Test ◽  
Deep Lake ◽  
Reflected Waves ◽  
Wind Speeds ◽  
Wave Characteristics ◽  
Wave Heights ◽  
Scale Test ◽  
Floating Bridges ◽  
The Waves

Wind waves in a lake have been observed to reflect from a barrier and to travel upwind for considerable distances. A model has been devised which provides a means of predicting the decay of these waves as a function of wind speed and direction with respect to the barrier. Two floating bridges across a deep lake have formed a convenient, full-scale test basin for the formation and observation of the reflected waves under a range of wind speeds and directions. Wave characteristics have been measured to a limited extent by photographic means, a portable wave probe and visually to provide seme verification of the results computed from the model. The measured and the predicted wave heights and the zones influenced by the waves were found to be in general qualitative agreement.

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.

Oblique wind waves generated by the instability of wind blowing over water

1996 ◽  
Vol 316 ◽  
pp. 163-172 ◽  
Author(s):  
L. C. Morland
Keyword(s):  
Gravity Waves ◽  
Wind Waves ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Mean Flow ◽  
Oblique Angle ◽  
Wind Speeds ◽  
The Mean ◽  
Directional Distributions ◽  
The Waves

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.

Numerical Simulation for Typhoon and Wave of Qiongzhou Strait

2016 ◽  
Author(s):  
Yanan Xu
Keyword(s):  
Southern China ◽  
Numerical Models ◽  
Wave Model ◽  
Numerical Approach ◽  
Wind Speeds ◽  
Qiongzhou Strait ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
The Waves ◽  
Simulated Wind

Southern China has been subject to some of the deadliest typhoons in history with records going back over a thousand years. Before the large waves associated with a typhoon reach the mainland of China there is a delay between the typhoon reaching landfall and the time of the extreme waves arriving. This paper focuses on an approach to simulate this lag in the waves reaching landfall in the Qiongzhou Strait in southern China. A numerical approach has been adopted to simulate the typhoon and wave processes using a parametric typhoon model and the SWAN wave model. Two typhoon events are simulated (typhoon Kai-Tak in 2012 and typhoon Jebi in 2013) and used to tune the parameters for the numerical models. The simulated wind speeds and significant wave heights of the typhoon are compared with measured data. For the simulation of typhoon Kai-Tak, the correlation coefficient gives an 87% agreement between the simulated and measured values of wave height with a standard deviation of 0.29 m. For typhoon Jebi the fit is less good (66%). However, the simulation results have provided insight into improving the parametric typhoon model.

scholarly journals EXPERIMENTAL STUDY OF WIND WAVES GENERATED ON CURRENTS

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.

scholarly journals THE CHARACTERISTICS OF WIND-WAVES GENERATED IN THE LABORATORY

1968 ◽  
Vol 1 (11) ◽  
pp. 4
Author(s):  
Theodore E. Lee
Keyword(s):  
Wind Wave ◽  
Wind Waves ◽  
Ocean Waves ◽  
Coastal Engineering ◽  
Wave Period ◽  
Zero Crossing ◽  
Wave Data ◽  
Wave Characteristics ◽  
Significant Correction ◽  
Wave Heights

Wind-wave characteristics were recorded in the laboratory for the primary purposes of (a) analysis of the probability distribution of wave height and wave period with wind speed, water depth, and fetch length as major parameters, and (b) comparison of the test results with existing theory and empirical formulae. An important aspect of this study was to test the validity of the Tucker and Draper method (Draper, 1966) for the presentation of ocean wave data as applicable to wave-data analysis for simulated wind waves. It was interesting to note that some corrections were necessary when the method proposed by Draper at the 10th Coastal Engineering Conference was used for analyzing waves generated in the laboratory. Approximately a positive 20% correction was necessary for this study in which the wave spectra distribution is of very narrow range, the wave width parametere = V1-(T /T ) varles from 0.25 to 0.50, where Tc and T2 represent crest wave period ana zero-crossing wave period, respectively. However, only a negative 5% correction was necessary when the method was used to analyze sea waves (e = 0 73 to 0 76) measured off the shoreline near Look Laboratory Therefore, it was concluded that the Tucker and Draper Method is quite feasible for engineering purposes in analyzing wind-waves having a spectral width parameter of 0.60 to 0.75 The experimental data were compared with those wave heights predicted by the Darbyshire formulas (Francis, 1959) developed for ocean waves. A significant correction factor was necessary for laboratory waves produced by low-speed wi nds. The "fetch graph" was prepared and compared with those developed theoretically by Hino (1966) and empirically by Ijima and Tang (1966) at the 10th Conference on Coastal Engineering, Tokyo, Japan Comparison was also made with the previous empirical formulae by Bretschneider (1951, 1957), Sverdrup and Munk (1947), and Wilson (1961,1962). The experimental results compared well with the Hino theory for both wave heights and wave periods, and fairly well with Bretschneider's fetch graph for wave heights The difference in the comparison of wave data with other investigators is illustrated in this paper. It is recommended that further study be made with emphasis on (a) theoretical and experimental studies of wind-wave characteristics on pre-existing waves, particularly moving storms, (b) wave-energy spectra involving stochastic characteristics and extreme values of wind waves

scholarly journals Wave Regime and Lithodynamics in the Region of the Western Crimea Accumulative Coasts

2020 ◽  
Vol 27 (4) ◽  
Author(s):  
Yu. N. Goryachkin ◽  
V. V. Fomin ◽  
◽  
Keyword(s):  
Black Sea ◽  
Opposite Direction ◽  
Wind Waves ◽  
Reanalysis Data ◽  
The Black Sea ◽  
Wave Regime ◽  
Wave Characteristics ◽  
Convergence Zones ◽  
The Waves

Purpose. The paper is aimed at obtaining the wave regime characteristics in the region of the Western Crimea accumulative coast, at constructing the scheme of the sediment along-coastal fluxes for various wind directions, at analyzing the previous notions on the lithodynamical processes in the region under study and their comparison with the obtained results. Methods and Results. The wave regime was analyzed using the results of the retrospective calculations of wind waves in the Black Sea derived due to the model SWAN and based on the ERA-Interim atmospheric reanalysis data for 1979–2018. The data of retrospective calculations performed by the method of annual maximums yielded the parameters of the waves of various repeatability. The sediment along-coastal flux was simulated and the schemes for six wind directions were constructed by the method including model values of the wave characteristics. Conclusions. Operative and extreme characteristics of the wind waves in the region under study are obtained. It is shown that in the above-mentioned area, the most intense sediment along-coastal fluxes occur being affected by the waves formed by the western, southwestern and southern winds. The northwestern and western winds give rise to the sediment main flux directed to the east. At the western wind, to the southeast from the Donuzlav sandbar and in the coast concavities, the sediments are transported in the opposite direction. When the winds are southwestern and southern, the sediment along-coastal flux move from the Cape Uret to Lake Donuzlav northern spit, where it meets the oppositely directed flux. To the southeast from Lake Donuzlav, the multidirectional fluxes arise; at that, in the coast concavities their convergence zones are formed. At the southeastern and eastern winds, the sediment along-coastal fluxes’ capacity decreases sharply; the fluxes are of multidirectional character and they form not a single flux on any of the long stretches of the coastline.

Roll Stabilization of Small Ships

1994 ◽  
Vol 31 (04) ◽  
pp. 286-295
Author(s):  
John P. Martin
Keyword(s):  
Full Scale ◽  
Test Results ◽  
Full Scale Test ◽  
Wave Heights ◽  
Scale Test ◽  
Roll Stabilization

The effect of ship size on the roll response of smaller vessels is reviewed. Particular attention is paid to the prevalence of the shorter wave heights and lengths that will cause heavy, resonant rolling of ships with short natural roll periods. The choices of various stabilizer types for the general classifications of small ships are reviewed. Model basin and full-scale test results of these ships with and without any type of stabilizer are presented. Particular attention is paid to ship types recently bid or delivered.

Full-Scale Test on Coupled Thermo-Hydro-Mechanical Processes in Engineered Barrier System

1994 ◽  
Vol 1 (1) ◽  
pp. 77-83
Author(s):  
Yoshiji Moro ◽  
Tomoo Fujita ◽  
Takeshi Kanno ◽  
Akira Kobayashi
Keyword(s):  
Full Scale ◽  
Full Scale Test ◽  
Scale Test ◽  
Engineered Barrier

The assessment of particulate matter (PM2.5) removal efficiency on air cleaner products through full scale test in Korea

2019 ◽  
Vol 18 (1) ◽  
pp. 76-80 ◽  
Author(s):  
Kichul Kim ◽  
Pil-Ju Park ◽  
Soomi Eo ◽  
Seungmi Kwon ◽  
Kwangrae Kim ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Removal Efficiency ◽  
Full Scale ◽  
Full Scale Test ◽  
Air Cleaner ◽  
Scale Test
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