scholarly journals A THEORY ON THE FETCH GRAPH, THE ROUGHNESS OF THE SEA AND THE ENERGY TRANSFER BETWEEN WIND AND WAVE

1966 ◽  
Vol 1 (10) ◽  
pp. 2
Author(s):  
Mikio Hino
Keyword(s):  
Experimental Data ◽  
Energy Transfer ◽  
Energy Dissipation ◽  
Basic Principle ◽  
Wind Wave ◽  
Peak Frequency ◽  
Wave Spectra ◽  
Total Drag ◽  
Wave Characteristics ◽  
Fundamental Mechanism

It is the aim of this paper to give theoretical derivations of the windwave characteristics from a viewpoint of fundamental mechanism of wind-wave generation. A hypothesis is proposed as a basic principle of the air-sea interaction, which asserts the maximum ratio of the energy transfer from wind to wave to the energy dissipation within wind. As the theoretical consequences of the hypothesis combined with the recent theories on wind-wave spectra by Miles and Phillips, wind-wave characteristics such as the fetch graph, the roughness of the sea, the spectral peak frequency, the ratio of pressure contribution to total drag and the energy transfer from wind to wave are derived with remarkable agreements with experimental data.

Third Generation Wind Wave Model Frequency Dependence of the White-Capping Dissipation Source Function

2002 ◽  
Author(s):  
Eustorgio Meza ◽  
Jun Zhang ◽  
Alejandro Olivares ◽  
Jorge Brambila
Keyword(s):  
Energy Dissipation ◽  
Energy Density ◽  
Frequency Dependence ◽  
Source Function ◽  
Wind Wave ◽  
Wave Model ◽  
Peak Frequency ◽  
Third Generation ◽  
Empirical Formulas ◽  
Transient Wave

This paper proposes new frequency dependence for the empirical formulas presently used to determine wave energy dissipation in ocean wave models. Using an energy focusing technique, several unidirectional transient wave trains were generated. Each of the transient wave train contained an isolated plunging or spilling breaker. By comparing the energy spectra of free-wave components before and after breaker it was found that: 1)the energy loss as function of frequency is almost exclusively from wave components at frequencies higher than the spectral peak frequency; 2)although the energy density of the wave components near the peak frequency are the largest, they do not significantly gain or lose energy after breaking; and 3)wave components of frequencies significantly below or near the peak frequency gain a small portion (about 12%) of energy lost by the high-frequency waves. The empirical formulas presently used to determine white-capping dissipation (Komen et al. 1994; Tolman and Chalikov 1996; Booij 1999) do not agree with the above spectral distribution of energy dissipation. Analysis of the dissipation distribution obtained by Meza et al. (2000), suggest that the dependence of the dissipation rate on the frequency should be described by, (ωωp)(1−(ωωp)E(ω), where ω is the wave frequency, ωp is the spectral peak frequency and E(ω) is the energy density spectrum. An energy dissipation source function with such a frequency dependence is being implemented and tested in a third generation wind wave model.

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.

Upper bounds on the energy dissipation in turbulent precession

1996 ◽  
Vol 321 ◽  
pp. 335-370 ◽  
Author(s):  
R. R. Kerswell
Keyword(s):  
Experimental Data ◽  
Energy Dissipation ◽  
Viscous Dissipation ◽  
Upper Bound ◽  
Dissipation Rate ◽  
Oblate Spheroid ◽  
Upper Bounds ◽  
Precession Rate ◽  
Long Cylinder

Rigorous upper bounds on the viscous dissipation rate are identified for two commonly studied precessing fluid-filled configurations: an oblate spheroid and a long cylinder. The latter represents an interesting new application of the upper-bounding techniques developed by Howard and Busse. A novel ‘background’ method recently introduced by Doering & Constantin is also used to deduce in both instances an upper bound which is independent of the fluid's viscosity and the forcing precession rate. Experimental data provide some evidence that the observed viscous dissipation rate mirrors this behaviour at sufficiently high precessional forcing. Implications are then discussed for the Earth's precessional response.

scholarly journals The calculation of TV, VT, VV, VV' − rate coefficients for the collisions of the main atmospheric components

1998 ◽  
Vol 16 (7) ◽  
pp. 838-846 ◽  
Author(s):  
A. S. Kirillov
Keyword(s):  
Experimental Data ◽  
Energy Transfer ◽  
Vibrational Energy ◽  
Relaxation Times ◽  
Atmospheric Composition ◽  
Rate Coefficients ◽  
Frequency Change ◽  
Vibrational Energy Transfer ◽  
Ion Chemistry ◽  
Vibrationally Excited

Abstract. The first-order perturbation approximation is applied to calculate the rate coefficients of vibrational energy transfer in collisions involving vibrationally excited molecules in the absence of non-adiabatic transitions. The factors of molecular attraction, oscillator frequency change, anharmonicity, 3-dimensionality and quasiclassical motion have been taken into account in the approximation. The analytical expressions presented have been normalized on experimental data of VT-relaxation times in N2 and O2 to obtain the steric factors and the extent of repulsive exchange potentials in collisions N2-N2 and O2-O2. The approach was applied to calculate the rate coefficients of vibrational-vibrational energy transfer in the collisions N2-N2, O2-O2 and N2-O2. It is shown that there is good agreement between our calculations and experimental data for all cases of energy transfer considered.Key words. Ionosphere (Auroral ionosphere; ion chemistry and composition). Atmospheric composition and structure (Aciglow and aurora).

scholarly journals Loop-Type Wave-Generation Method for Generating Wind Waves under Long-Fetch Conditions

2017 ◽  
Vol 34 (10) ◽  
pp. 2129-2139 ◽  
Author(s):  
Naohisa Takagaki ◽  
Satoru Komori ◽  
Mizuki Ishida ◽  
Koji Iwano ◽  
Ryoichi Kurose ◽  
...  
Keyword(s):  
Wind Wave ◽  
Wind Waves ◽  
Peak Frequency ◽  
Wave Generation ◽  
New Wave ◽  
Wave Tank ◽  
Irregular Wave ◽  
Wind Speeds ◽  
Type Wave ◽  
Wave Generator

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.

scholarly journals THE ONE-DIMENSIONAL WAVE SPECTRA AT LIMITED FETCH

1972 ◽  
Vol 1 (13) ◽  
pp. 13
Author(s):  
Hisashi Mitsuyasu
Keyword(s):  
Similarity Theory ◽  
Wind Waves ◽  
Laboratory Data ◽  
Peak Frequency ◽  
Wave Spectra ◽  
One Dimensional ◽  
Wide Range ◽  
Laboratory Tank ◽  
The One ◽  
Dimensional Wave

The data for the spectra of wind-generated waves measured in a laboratory tank and in a bay are analyzed using the similarity theory of Kitaigorodski, and the one-dimensional spectra of fetch-limited wind waves are determined from the data. The combined field and laboratory data cover such a wide range of dimensionless fetch F (= gF/u2 ) as F : 102 ~ 10 . The fetch relations for the growthes of spectral peak frequency u)m and of total energy E of the spectrum are derived from the proposed spectra, which are consistent with those derived directly from the measured spectra.

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