共查询到20条相似文献，搜索用时 15 毫秒
1.
胡定明 《海洋学报(英文版)》1986,5(1):1-14
An analytical solution for the velocity potential of linear waves traveling over sloping beaches is obtained in the present paper, the restriction to the solution, i. e. the cube of bottom slope a being negligible. When the terms of order of a2 are neglected, the solution is the same as that presented by Biesel in 1951[1]. When the terms of order of a2 are retained, the wave dispersion relation is corrected. Forthermore, the solution corrected to any higher order of a can be obtained without difficulty by means of the disturbation method given by this paper". 相似文献
2.
洪广文 《海洋学报(英文版)》1982,1(1):144-154
Based on the perturbation method, a fourth order theory for nonlinear interactions among three dimensional gravity waves in water of any uniform depth is presented in this paper. Two cases are considered: ( i ) wave number vectors fixed, frequencies perturbed, and ( ii ) wave number vectors and frequencies both fixed. According to this solution, expressions of thesame order for progressive waves, short-crested waves and nonlinear interaction between wave and vertical wall are also derived' 相似文献
3.
Based on the full water-wave equation,a second-order analytic solution for nonlinear interaction of short edge waves on a plane sloping bottom is presented in this paper.For special case of slope angle β=π/2,this solution can reduced to the same order solution of deep water gravity surface waves traveling along parallel coastline.Interactions between two edge waves including progressive,standing and partially reflected standing waves are also discussed.The unified analytic expressions with transfer functions for kinematic-dynamic elements of edge waves are also given.The random model of the unified wave motion processes for linear and nonlinear irregular edge waves is formulated,and the corresponding theoretical autocorrelation and spectral density functions of the first and the second orders are derived.The boundary conditions for the determination of the parameters of short edge wave are suggested,that may be seen as one special simple edge wave excitation mechanism and an extension to the sea wave refraction theory.Finally some computation results are demonstrated. 相似文献
4.
An extremely large (“freak”) wave is a typical though rare phenomenon observed in the sea. Special theories (for example, the modulation instability theory) were developed to explain mechanics and appearance of freak waves as a result of nonlinear wave-wave interactions. In this paper, it is demonstrated that the freak wave appearance can be also explained by superposition of linear modes with the realistic spectrum. The integral probability of trough-to-crest waves is calculated by two methods: the first one is based on the results of the numerical simulation of a wave field evolution performed with one-dimensional and two-dimensional nonlinear models. The second method is based on calculation of the same probability over the ensembles of wave fields constructed as a superposition of linear waves with random phases and the spectrum similar to that used in the nonlinear simulations. It is shown that the integral probabilities for nonlinear and linear cases are of the same order of values 相似文献
5.
According to the results of model test in a wave channel, some properties of irregular waves reflected by a vertical wall and the scouring patterns of the sand bottom in front of the wall are discussed in the present paper.The main conclusions of the action of regular standing waves on sand beds in front of a vertical wall are also mentioned briefly for comparison. It has been shown by analysis that the ultimate scouring depth could be on the safe side if the significant wave height is taken as the equivalent wave height in the regular wave test. 相似文献
6.
Because of shoaling, refraction, friction, and other effects, a surface-wave propagating on a gently sloping bottom of slope will eventually break. In this paper, by nonlinearizing the problem and using a perturbation method, an analytical solution for the velocity potential is derived to the second order for the bottom slope a and the wave steepness e in a Eulerian system. Then, the wave profile and the breaking wave characteristics are found by transforming the flow field into a Lagrangian system. By use of the kinematic stability parameter （K. S. P. ）, new theoretical breaker characteristics are derived. Thus, the linear theories of other scholars are extended to breaking waves. A Comparison of the present analytical solution with experimental studies of other scholars shows reasonable agreement except that the breaking depth is underestimated. 相似文献
7.
Feng Weibing Hong Guangwen
Ph. D Student Hohai University Nanjing .
Professor Hohai University Nanjing 《中国海洋工程》1995,(1)
An analytic-numerical solution of wave transformation in shoaling water is presented in this paper. The analytical expression for wave heights along the wave rays is derived in consideration of the combined effect of water depth shoaling, the wave refraction and the sea bottom friction. The wave rays (orthogonals) are calculated by a fourth order Runge-Kutta algorithm and the wave crest lines are computed by an iteration procedure. The numerical results are compared with analytical solution for a special case of parallel- straight contour shore and field data, and comparisons show that the proposed mathematical model and computation method are very useful and convenient for engineering application. 相似文献
8.
YAN Chenghua 《中国海洋工程》2001,(2):291-300
A two-dimensional nonlinear sloshing problem is analyzed by means of the fully nonlinear theory and time domain second order theory of water waves. Liquid sloshing in a rectangular container subjected to a horizontal excitation is sim-ulated by the finite element method. Comparisons between the two theories are made based on their numerical results, It is found that good agreement is obtained for the case of small amplitude oscillation and obvious differences occur for large amplitude excitation. Even though, the second order solution can still exhibit typical nonlinear features of nonlinear wave and can be used instead of the fully nonlinear theory. 相似文献
9.
Li Yucheng Dong Guohai Professor Dalian University of Technology Dalian
Doctor of Engineering Lecturer Dalian University of Technology Dalian 《中国海洋工程》1993,(2)
- Experimental study and theoretical analysis show that the critical value of relative wave height (H/ d)b given by Goda and the critical wave steepness (H/ L)b given by Michell and Miche can be adopted as the spilling breaking indices of regular waves. According to the same principle, a systematic theoretical analysis and experiment of irregular waves have been done by the authors in order to solve the breaking problem of irregular waves. It is indicated that the authors' method for determining wave breaking of regular waves can also be used for irregular waves. 相似文献
10.
With the presence of wind waves, the swaying of survey vessel may effect the quality of sub-bottom profiler records and, therefore, it is necessary to correct the distortions induced by wave action. A major issue is to distinguish wind wave effect and real bedforms such as sand waves. In this paper, a bandstop filter is designed according to the frequency features of wind wave effect to treat the distortion of seabed topography by wind waves. The technique is used to correct the sub-bottom profile in order to eliminate the wave-induced distortions for the sub-bottom profile records from the Yangtze Estuary. This study shows that the undulate seabed record is resulted from wave action, rather than the presence of sand waves, and the filtration technique helps to eliminate the wave effect and recover the real morphology of seabed and the sediment sequence underneath. In addition, a method for data processing is proposed for the case that the record indeed represents a combination of wave effects and real bedforms. 相似文献
11.
A numerical model is developed that can predict the interaction of regular waves normally incident upon a curtainwall-pile breakwater; the upper part of which is a vertical wall and the lower part consists of an array of vertical piles. The numerical model is based on an eigenfunction expansion method, and utilizes a boundary condition nearby the vertical piles that accounts for wave energy dissipation. Numerical solution comprises a finite number of terms, which is a superposition of propagating waves and a series of evanescent waves. The modeling is validated by comparison with previous experimental studies and overall agreement between measurement and calculation is fairly good. The numerical results are related to reflection, transmission, and dissipation coefficient; wave run-up, wave force, and wave overturning moment are also presented. Effect of porosity, relative draft, and relative water depth are discussed; the choice of suitable range of them is described. The relative draft is more effective for shallow water waves. Model shows decrease in relative draft and leads to reduction of relative wave force, overturning moment, and runup. It is shown that curtainwall-pile breakwaters can operate both effectively and efficiently in the range of relative draft between 0.15 and 0.75. The range 0.5 to 0.2 is also recommended for porosity. 相似文献
12.
Chung-RenCHOU Teng-WeiLIN Ruey-SyanSHIH JohnZ.YIM 《中国海洋工程》2005,19(1):37-48
Measurements of wave heights with image sequences from a Charged Coupled Device(CCD) camera were made. Sinusoidal, as well as unidirectional and directional, waves were used for the experiments. A transfer function was obtained by calibration of the magnitudes of the gray values of the images against the results of wave gauge measurements for directional waves. With this transfer function, wave heights for regular waves were deduced. It is shown that the average relative errors are smaller than 16% for both unidirectional and directional waves. 相似文献
13.
Based on a set of fully nonlinear Boussinesq equations up to the order of O（μ^2, ε^3μ^2） （where ε is the ratio of wave amplitude to water depth and ,μ is the ratio of water depth to wave length） a numerical wave model is formulated. The model＇s linear dispersion is acceptably accurate to μ ≌ 1.0, which is confirmed by comparisons between the simulat- ed and measured time series of the regular waves propagating on a submerged bar. The moving shoreline is treated numer- ically by replacing the solid beach with a permeable beach. Run-up of nonbreaking waves is verified against the analytical solution for nonlinear shallow water waves. The inclusion of wave breaking is fulfilled by introducing an eddy term in the momentum equation to serve as the breaking wave force term to dissipate wave energy in the surf zone. The model is applied to cross-shore motions of regular waves including various types of breaking on plane sloping beaches. Comparisons of the model test results comprising spatial distribution of wave height and mean water level with experimental data are presented. 相似文献
14.
A numerical model for wave propagation in a harbour is verified by use of physical models.The extended time-dependent mild slope equation is employed as the governing equation,and the model is solved by use of ADI method containing the relaxation factor.Firstly,the reflection coefficient of waves in front of rubble-mound breakwaters under oblique incident waves is determined through physical model tests,and it is regarded as the basis for simulating partial reflection boundaries of the numerical model.Then model tests on refraction,diffraction and reflection of waves in a harbour are performed to measure wave height distribution.Comparative results between physical and numerical model tests show that the present numerical model can satisfactorily simulate the propagation of regular and irregular waves in a harbour with complex topography and boundary conditions. 相似文献
15.
In the first part of our studies, the unified solutions of existing waves have been obtained by using the linear wave equations without making the assumptions of irrotation and hydrostatic pressure. In this paper, the second part of our studies, we shall devote to linear long wave equations without the assumption of hydrostatic pressure. All the solutions in the case of ω=f are found. A set of solutions is also obtained, with a similarity to the unified solutions of the Sverdrup waves and the Poincare waves, but the corresponding waves represented by such a set have a different vertical structure of velocities. The set is not included in the solutions of linear long wave equations under the assumption of hydrostatic pressure and, therefore, is regarded as possible waves filtered out by the assumption of hydrostatic pressure. 相似文献
16.
This paper studies the continuous evolution of breaking wave for the surface water waves propagating on a sloping beach. A Lagrangian asymptotic solution is derived. According to the solution coupled with the wave breaking criteria and the equations of water particles motion, the wave deformation and the continuous wave breaking processes for the progressive water waves propagating on a sloping bottom can be derived. A series of experiments are also conducted to compare with the theoretical solution. The results show that the present solution can reasonably describe the plunging or spilling wave breaking phenomenon. 相似文献
17.
Regular and irregular wave forces acting on vertical walls are studied by a previously developed numerical model. The computed wave forces are compared with the available experimental data to verify the numerical model, and satisfactory agreements are obtained. The variation of wave forces with incident angles and the shape of simultaneous pressure distribution are investigated, and the comparisons between numerical results and Goda＇ s predictions are also carried out. It is concluded that the maximum wave forces acting on the unit length of vertical wall is often induced by the obliquely incident waves instead of normally incident waves, while Goda＇ s formula may be inapplicable for oblique wave incidence. The shape of simultaneous pressure distribution is not significantly influenced by incident angles, and it can be favorably predicted by Goda＇ s formula. When regular wave heights are taken as the same as irregular wave height H1%, the irregular wave forces Ph. 1% are slightly larger than regular wave forces in most cases. 相似文献
18.
有界赤道大洋波包解及其年际年代际变率 总被引：1，自引：0，他引：1
Linearized shallow water perturbation equations with approximation in an equatorial β plane are used to obtain the analytical solution of wave packet anomalies in the upper bounded equatorial ocean. The main results are as follows. The wave packet is a superposition of eastward travelling Kelvin waves and westward travelling Rossby waves with the slowest speed, and satisfies the boundary conditions of eastern and western coasts, respectively.The decay coefficient of this solution to the north and south sides of the equator is inversely proportional only to the phase velocity of Kelvin waves in the upper water. The oscillation frequency of the wave packet, which is also the natural frequency of the ocean, is proportional to its mode number and the phase velocity of Kelvin waves and is inversely proportional to the length of the equatorial ocean in the east-west direction. The flow anomalies of the wave packet of Mode 1 most of the time appear as zonal flows with the same direction. They reach the maximum at the center of the equatorial ocean and decay rapidly away from the equator, manifested as equatorially trapped waves. The flow anomalies of the wave packet of Mode 2 appear as the zonal flows with the same direction most of the time in half of the ocean, and are always 0 at the center of the entire ocean which indicates stagnation, while decaying away from the equator with the same speed as that of Mode 1. The spatial structure and oscillation period of the wave packet solution of Mode 1 and Mode 2 are consistent with the changing periods of the surface spatial field and time coefficient of the first and second modes of complex empirical orthogonal function(EOF)analysis of flow anomalies in the actual equatorial ocean. This indicates that the solution does exist in the real ocean, and that El Ni?o-Southern Oscillation(ENSO) and Indian Ocean dipole(IOD) are both related to Mode 2.After considering the Indonesian throughflow, we can obtain the length of bounded equatorial ocean by taking the sum of that of the tropical Indian Ocean and the tropical Pacific Ocean, thus this wave packet can also explain the decadal variability(about 20 a) of the equatorial Pacific and Indian Oceans. 相似文献
19.
A novel theoretical approach is applied to predict the propagation and transformation of transient nonlinear waves on a current. The problem was solved by applying an eigenfunction expansion method and the derived semi-analytical solution was employed to study the transformation of wave profile and the evolution of wave spectrum arising from the nonlinear interactions of wave components in a wave train which may lead to the formation of very large waves. The results show that the propagation of wave trains is significantly affected by a current. A relatively small current may substantially affect wave train components and the wave train shape. This is observed for both opposing and following current. The results demonstrate that the application of the nonlinear model has a substantial effect on the shape of a wave spectrum. A train of originally linear and very narrow-banded waves changes its one-peak spectrum to a multi-peak one in a fairly short distance from an initial position. The discrepancies between the wave trains predicted by applying the linear and nonlinear models increase with the increasing wavelength and become significant in shallow water even for waves with low steepness. Laboratory experiments were conducted in a wave flume to verify theoretical results. The free-surface elevations recorded by a system of wave gauges are compared with the results provided by the nonlinear model. Additional verification was achieved by applying a Fourier analysis and comparing wave amplitude spectra obtained from theoretical results with experimental data. A reasonable agreement between theoretical results and experimental data is observed for both amplitudes and phases. The model predicts fairly well multi-peak spectra, including wave spectra with significant nonlinear wave components. 相似文献
20.
Hong Guangwen 《海洋学报(英文版)》1992,11(2):287-303
An exact analytic solution for wave diffraction by wedge or corner with arbitrary angle (rπ) and reflection coefficients (R0 and Rr) is presented in this paper. It is expressed in two forms-series and integral representations, corresponding recurrence relation and asymptotic expressions are also derived. The solution is simplified for some special cases of rπ. For Rr= R0,r= 1/N and Rr≠R0,r = 1/2N, the solution can be reduced to linear superpositions of incident and partially reflected waves, hence a nonlinear solution of forth order for this problem can be obtained by using the author's theory of nonlinear interaction among gravity surface waves. The given solution is related to inhomogeneous Robin boundary conditions, which include the Neumann boundary conditions usually accepted in wave diffraction theory. 相似文献