Wave-height distributions and nonlinear effects   总被引：2，自引：0，他引：2  

M. Aziz Tayfun  Francesco Fedele 《Ocean Engineering》2007,34(11-12):1631-1649

Theoretical distributions proposed for describing the crest-to-trough heights of linear waves are reviewed briefly. To explore the effects of nonlinearities, these are generalized to second-order waves, utilizing quasi-deterministic results on the expected shape of large waves. The efficacy of Gram–Charlier models in describing the effects of third-order nonlinearities on the distributions of wave heights, crests and troughs are examined in detail. All models and a fifth-order Stokes–Rayleigh type model recently proposed are compared with linear and nonlinear waves simulated from the JONSWAP spectrum representative of long-crested extreme seas, and also with oceanic data gathered in the North Sea. Uncertainties arising from the variability of probability estimates derived from sample populations of limited size are considered. Ultimately, the comparisons show that nonlinearities do not have any discernable effect on the crest-to-trough heights of oceanic waves. Most of the linear models considered yield similar and reasonable predictions of the observed data trends. Gram–Charlier type distributions seem neither effective nor particularly useful in describing the statistics of large wave heights or crests under oceanic conditions. However, they do surprisingly well in predicting unusually large wave heights and crests observed in some 2D wave-flume experiments and 3D numerical simulations of long-crested narrow-band random waves.  相似文献   

Wave Dispersion Study in the Indian Ocean-Tsunami of December 26, 2004     

Juan Horrillo  Zygmunt Kowalik  Yoshinori Shigihara 《Marine Geodesy》2006,29(3):149-166

A numerical study which takes into account wave dispersion effects has been carried out in the Indian Ocean to reproduce the initial stage of wave propagation of the tsunami event that occurred on December 26, 2004. Three different numerical models have been used: the nonlinear shallow water (nondispersive), the nonlinear Boussinesq, and the full Navier-Stokes aided by the volume of fluid method to track the free surface. Numerical model results are compared against each other. General features of the wave propagation agreed very well in all numerical studies. However some important differences are observed in the wave patterns, i.e., the development in time of the wave front is shown to be strongly connected to the dispersion effects. Discussions and conclusions are made about the spatial and temporal distribution of the free surface reaffirming that the dispersion mechanism is important for tsunami hazard mitigation.  相似文献   

The retrieval of the nonlinear random waves from the non-Gaussian characteristics of the sea surface elevation distribution     

Liu Xin''an  Huang Peiji 《海洋学报(英文版)》1993,12(4):499-510

In this paper, without recourse to the nonlinear dynamical equations of the waves, the nonlinear random waves are retrieved from the non-Gaussian characteristic of the sea surface elevation distribution. The question of coincidence of the nonlinear wave profile, spectrum and its distributions of maximum (or minimum) values of the sea surface elevation with results derived from some existing nonlinear theories is expounded under the narrow-band spectrum condition. Taking the shoaling sea wave as an example, the nonlinear random wave process and its spectrum in shallow water are retrieved from both the non-Gaussian characteristics of the sea surface elevation distribution in shallow water and the normal sea waves in deep water and compared with the values actually measured. Results show that they can coincide with the actually measured values quite well, thus, this can confirm that the method proposed in this paper is feasible.  相似文献   

北部湾沿岸海区设计波浪的确定     

滕学春  吴秀杰  刘丽惠 《海洋科学进展》1995,(3)

本文基于北部湾沿岸海区多年的实测资料，于不同海区主浪向和次主浪向分别取年极值波高为样本资料．采用Ｐ－Ⅲ型和短期测波资料频率分析方法，分别估算了各海区不同重现期的设计波高，并依据式（１）计算出相应的平均周期。尽管样本资料和估算方法不变，但每次估算的结果互不相同，其差异甚至很大．利用Ｋｏｌｍｏｇｏｒｏｆｆ等适合度方法检验所得的结果，能够准确地判断出沿岸各海区不同重现期的最佳设计波浪。  相似文献   

Preliminary study on the dynamic mechanism of the deep equatorial jets     

Wu Dexing 《海洋学报(英文版)》1994,13(4):465-474

Ｐｒｅｌｉｍｉｎａｒｙｓｔｕｄｙｏｎｔｈｅｄｙｎａｍｉｃｍｅｃｈａｎｉｓｍｏｆｔｈｅｄｅｅｐｅｑｕａｔｏｒｉａｌｊｅｔｓ￥ＷｕＤｅｘｉｎｇ（ＲｅｃｅｉｖｅｄＤｅｃｅｍｂｅｒ１５，１９９３；ａｃｃｅｐｔｅｄＭａｒｃｈ７，１９９４）（Ｉｎｓｔｉｔｕｔｅｏ...  相似文献   

Verification of linear theory for particle velocities in wind waves based on field measurements     

J.A. Battjes  J. van Heteren 《Applied Ocean Research》1984,6(4):187-196

Analyses are presented of field measurements of spectral transfer functions between surface elevation and subsurface three-dimensional particle velocity in wind-generated waves, in conditions ranging from young seas to old swells. The results are in agreement with the linear theory predictions to within the measurement error margin, which is estimated to be ± 5% for the gain functions and ± 4° in phase as far as the possible systemic errors are concerned. No correlation is found of the degree of agreement between measurements and linear theory with wave age or wave sleepness.  相似文献   

Multidirectional wave transformation around detached breakwaters     

S. Ilic  A.J. van der Westhuysen  J.A. Roelvink  A.J. Chadwick 《Coastal Engineering》2007

The performance of the new wave diffraction feature of the shallow-water spectral model SWAN, particularly its ability to predict the multidirectional wave transformation around shore-parallel emerged breakwaters is examined using laboratory and field data. Comparison between model predictions and field measurements of directional spectra was used to identify the importance of various wave transformation processes in the evolution of the directional wave field. First, the model was evaluated against laboratory measurements of diffracted multidirectional waves around a breakwater shoulder. Excellent agreement between the model predictions and measurements was found for broad frequency and directional spectra. The performance of the model worsened with decreasing frequency and directional spread. Next, the performance of the model with regard to diffraction–refraction was assessed for directional wave spectra around detached breakwaters. Seven different field cases were considered: three wind–sea spectra with broad frequency and directional distributions, each coming from a different direction; two swell–sea bimodal spectra; and two swell spectra with narrow frequency and directional distributions. The new diffraction functionality in SWAN improved the prediction of wave heights around shore-parallel breakwaters. Processes such as beach reflection and wave transmission through breakwaters seem to have a significant role on transformation of swell waves behind the breakwaters. Bottom friction and wave–current interactions were less important, while the difference in frequency and directional distribution might be associated with seiching.  相似文献   

A note on wave energy dissipation over steep beaches     

T.T. Janssen  J.A. Battjes 《Coastal Engineering》2007

This paper revisits the derivation of the parametric surf zone model proposed by Baldock et al. [Baldock, T. E., Holmes, P., Bunker, S. & Van Weert, P. 1998 Cross-shore hydrodynamics within an unsaturated surf zone. Coast. Eng. 34, 173–196.]. We show that a consistent use of the proposed Rayleigh distribution for surf zone wave heights results in modification of the expressions for the bulk dissipation rate and enhanced dissipation levels on steep beaches and over-saturated surf zone conditions. As a consequence, the modification proposed herein renders the model robust even on steep beaches where it could otherwise develop a shoreline singularity.  相似文献   

Temporal Variability of High Vertical Wavenumber Shear over the Izu-Ogasawara Ridge     

Maki?NagasawaEmail author  Toshiyuki?Hibiya  Naoki?Furuichi  Shogo?Takagi 《Journal of Oceanography》2005,61(6):1101-1105

Recent numerical studies (Hibiya et al., 1996, 1998, 2002) showed that the energy cascade across the internal wave spectrum down to small dissipation scales was under strong control of parametric subharmonic instabilities (PSI) which transfer energy from low vertical mode double-inertial frequency internal waves to high vertical mode near-inertial internal waves. To see whether or not the numerically-predicted energy cascade process is actually dominant in the real deep ocean, we examine the temporal variability of vertical profiles of horizontal velocity observed by deploying a number of expendable current profilers (XCPs) at one location near the Izu-Ogasawara Ridge. By calculating EOFs, we find the observed velocity profiles are dominated by low mode semidiurnal (∼double-inertial frequency) internal tides and high mode near-inertial internal waves. Furthermore, we find that the WKB-stretched vertical scales of the near-inertial current shear are about 250 sm and 100 sm. The observed features are reasonably explained if the energy cascade down to small dissipation scales is dominated by PSI.  相似文献   

Simulating nonlinear waves on the free surface in surf zones with two-dimensional sloping beach     

Young-Gill Lee  Jae-Kyung Heo 《Ocean Engineering》2005,32(1):206-84

Unsteady nonlinear wave motions on the free surface in shallow water and over slopes of various geometries are numerically simulated using a finite difference method in rectangular grid system. Two-dimensional Navier–Stokes equations and the continuity equation are used for the computations. Irregular leg lengths and stars are employed near the boundaries of body and free surface to satisfy the boundary conditions. Also, the free surface which consists of markers or segments is determined every time step with the satisfaction of kinematic and dynamic free surface conditions. Moreover, marker-density method is also adopted to allow plunging jets impinging on the free surface. Either linear or Stokes wave theory is employed for the generation of waves on the inflow boundary. For the simulation of wave breaking phenomena, the computations are carried out with various wave periods and sea bottom slopes in surf zone. The results are compared with other existing computational and experimental results. Agreement between the experimental data and the computation results is good.  相似文献