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1.
文中假定海面实际的海浪是由大小、周期、形状各异的一群外观海浪所组成,或者说是以外观海浪谱的外观表现来反映海面实际海浪的。还假定,每个外观海浪独立传播,独自受浅水作用,并不相互作用。据上述两点假定,作者提出了一种计算浅水波要素的方法。通过计算实例指出,在狂涛中,依本方法计算的平均波高比按我国“规范”方法计算的平均波高要偏低,而在狂浪以下海况中,则可能相反。应用本方法还可以得到一些“规范”方法无法得到的结果——浅水处的外观海浪谱与破碎带。 相似文献
2.
LAGFD-WAM海浪数值模式是一种第三代海浪数值模式，通过求解波数谱平衡方程，并考虑风输入、波浪破碎耗散、底摩擦耗散、波波非线性相互作用和波流相互作用等源函数，模拟波数空间下的海浪方向谱，并依此获得海浪的波高、周期和平均波向。该模式的一个显著特点是采用特征线嵌入格式求解海浪的传播。在进行浅水区域的海浪模拟时，特征线嵌入格式的数值计算方案是否合理对海浪数值模拟结果产生直接的影响。为此LAGFD-WAM海浪数值模式提出了一种新的特征线混合数值计算格式，并应用于浅水海浪数值模拟。结果表明，采用该计算方法，能够使数值模拟结果与实测结果很好符合。 相似文献
3.
风涌浪分离是研究风浪、涌浪各自特性的基础，但受限于海浪谱数据的匮乏，基于海浪谱的风涌浪分离方法难以普及应用，有效的解决办法是采用波浪观测中容易获取的基本波要素进行风涌浪分离。现有方法无法利用基本波要素全面计算出风浪、涌浪的比例及其特征参数，为此本文将机器学习引入到风涌浪分离中，以多层感知器模型为基础，提出了一种利用基本波要素、风要素准确计算出风涌浪参数的方法。该方法需要每个测站提供至少466笔、建议766笔及以上的实测波浪数据作为训练样本，适用于台湾海峡3个测站，在计算精度上显著优于基于海浪频谱的传统风涌浪分离方法，可为本海域缺乏海浪谱的测站提供替代性的风涌浪计算方案，有助于扩大实测风涌浪资料的来源，进而加强风涌浪分布特性以及预警预报研究。 相似文献
4.
海浪对直立堤作用力的研究 总被引：1，自引：0，他引：1
海浪对水工建筑物作用的研究是具有十分重要意义的.目前直立堤在海岸工程中仍然是一种广为采用的结构型式.众所周知,很早以来,人们就波浪对直立堤的作用力问题进行了广泛的研究,获得了不少成功的结果.但至今在工程设计中,关于海浪对直立堤作用力的计算方法仍是把复杂的海浪抽象成为规则波的形式,根据规则波的波高、周期来计算,并且大都借室内规则波的模型试验进行验证与订正.在这种计算过程中,目前多数在求得海浪参数时,是考虑了海浪的不规则性的,但在波压力计算本身,则又从规则波理论出发.因此,为建立工程上实用的海浪对直立堤作用力的计算方法,国内外都从各种途径进行着研究. 相似文献
5.
基于浅水斜坡地形的物理模型试验数据,考察SWAN模型对实验室小尺度浅水波浪的模拟效果,进而检验其浅水项的模拟精度。模拟中采用直接输入初始测点的实测海浪谱进行造波,重点考察浅水中三波相互作用和变浅破碎两个源项,对不同工况下,SWAN模式在水深条件变化下的有效波高、谱平均周期、海浪谱演化的模拟能力进行研究。研究表明:模拟的有效波高较符合实测波浪的增长和衰减,但谱平均周期计算值明显偏小;海浪谱的能量转移机制同实测有较大区别,频谱模拟结果出现高频高估、低频低估现象。对两个源项进行对比分析得出三波相互作用对海浪谱的能量转换影响远大于变浅破碎耗散。想要提高近岸区谱平均周期和海浪谱的模拟精度则SWAN模型中三波非线性项的计算精确度仍需更多研究和改进。 相似文献
6.
海浪和潮汐风暴潮耦合过程的数值研究 总被引：1，自引：0，他引：1
海浪和风暴潮是重要的海洋灾害。对它们的精确预测和预报对沿岸海洋灾害的风险评估及海洋工程的设计具有极其重要的社会和经济价值。过去人们本多对波浪和风暴潮单独进行预报。实际上，风既产生浪又产生风暴潮，因此它们的产生必然存在相互作用。本研究的目的就是要建立一个渤海高分辨率的双向耦合的海浪和潮汐风暴潮数值模式，研究各耦合机制的影响，以期为黄河三角洲沿岸风暴潮海浪漫堤、漫滩风险评估提供更为准确的海浪风暴潮预测预报结果。
作者在研究中基于国际上先进的第三代海浪数值模式和潮汐风暴潮模式，建立了渤海2''×2''的海浪和潮汐风暴潮耦合数值模式。耦合模式充分考虑了三个主要耦合物理机制：依赖海浪状态的表面风应力，波-流相互作用底应力和辐射应力。波浪模式主要基于国际上第三代WAM模式，并对其进行了浅水效应的改进，以包括浅水深度破碎引起的能量耗散；潮汐风暴潮模式计算中开边界考虑了10个主要分潮K1，O1，P1，Q1，M2，S2，N2，K2，Sa，Ssa。依赖海浪状态的表面风应力取自Donelan等(1993)的结果,波-流相互作用底应力取自Signell等(1990)对 Grant and Madsen(1979)简化的结果，辐射应力以海浪谱表示。耦合计算中，两个模式通过三个耦合机制双向传递所需参量。
运用胜利油田中心一号观测的2个同步浪、潮、流资料对所建的耦合模式进行了检验，并通过耦合和非耦合模式结果的对比对各耦合机制的影响效应进行分析研究。研究结果表明，不同物理机制对波高的影响主要由能量方程中以辐射应力表示的波流相互作用所决定；在波-潮耦合作用中，依赖波令的表面风应力和辐射应力对水位是正效应，而波流相互作用底应力对水位是负效应。三个物理机制的综合净效应是正，可增加水位达25cm。比较显示，耦合模式的结果无论对波高还是水位都比非耦合模式的结果好，特别在峰值处。
本研究显示耦合模式的结果将改进海浪和风暴潮的模拟精度。所建立的耦合模式将对渤海海浪和风暴潮预报精度的提高，以及为黄河三角洲近岸海浪和风暴潮灾害的风险评估，提供更可靠的参数，具有重要的价值。 相似文献
7.
海浪和潮汐风暴潮耦合过程的数值研究(英文) 总被引：1，自引：0，他引：1
海浪和风暴潮是重要的海洋灾害。对它们的精确预测和预报对沿岸海洋灾害的风险评估及海洋工程的设计具有极其重要的社会和经济价值。过去人们大多对波浪和风暴潮单独进行预报。实际上,风既产生浪又产生风暴潮,因此它们的产生必然存在相互作用。本研究的目的就是要建立一个渤海高分辨率的双向耦合的海浪和潮汐风暴潮数值模式,研究各耦合机制的影响,以期为黄河三角洲沿岸风暴潮海浪漫堤、漫滩风险评估提供更为准确的海浪风暴潮预测预报结果。作者在研究中基于国际上先进的第三代海浪数值模式和潮汐风暴潮模式,建立了渤海2′×2′的海浪和潮汐风暴潮耦合数值模式。耦合模式充分考虑了三个主要耦合物理机制:依赖海浪状态的表面风应力,波-流相互作用底应力和辐射应力。波浪模式主要基于国际上第三代WAM模式,并对其进行了浅水效应的改进,以包括浅水深度破碎引起的能量耗散;潮汐风暴潮模式计算中开边界考虑了10个主要分潮K1,O1,P1,Q1,M2,S2,N2,K2,Sa,Ssa。依赖海浪状态的表面风应力取自Donelan等(1993)的结果,波-流相互作用底应力取自Signell等(1990)对GrantandMadsen(1979)简化的结果,辐射应力以海浪谱表示。耦合计算中,两个模式通过三个耦合机制双向传递所需参量。运用胜利油田中心一号观测的2个同步浪、潮、流资料对所建的耦合模式进行了检验,并通过耦合和非耦合模式结果的对比对各耦合机制的影响效应进行分析研究。研究结果表明,不同物理机制对波高的影响主要由能量方程中以辐射应力表示的波流相互作用所决定;在波-潮耦合作用中,依赖波令的表面风应力和辐射应力对水位是正效应,而波流相互作用底应力对水位是负效应。三个物理机制的综合净效应是正,可增加水位达25cm。比较显示,耦合模式的结果无论对波高还是水位都比非耦合模式的结果好,特别在峰值处。本研究显示耦合模式的结果将改进海浪和风暴潮的模拟精度。所建立的耦合模式将对渤海海浪和风暴潮预报精度的提高,以及为黄河三角洲近岸海浪和风暴潮灾害的风险评估,提供更可靠的参数,具有重要的价值。 相似文献
8.
联合第三代浅水海浪模式SWAN和三维海流模式POM,建立考虑海浪影响的三维风暴潮模式,利用该模式,在渤黄海区域,对温带气旋830315诱发的风暴潮进行数值模拟,从海表风应力、辐射应力、底应力三方面入手,对海浪对风暴潮的影响进行了数值研究.研究表明:海浪通过风应力对风暴潮水位的影响最为显著,而波致辐射应力与依赖波流相互作用的底应力的影响只在渤海和北黄海相对明显;考虑海浪影响的风暴潮水住过程曲线模拟结果,比不考虑海浪影响的纯风暴潮模拟结果与实测水位曲线吻合的更好,尤其是在减水极值处,其相对误差不超过5.57%. 相似文献
9.
联合第三代浅水海浪模式SWAN和三维海流模式POM,建立考虑海浪影响的三维风暴潮模式,利用该模式,在渤黄海区域,对温带气旋830315诱发的风暴潮进行数值模拟,从海表风应力、辐射应力、底应力三方面入手,对海浪对风暴潮的影响进行了数值研究.研究表明海浪通过风应力对风暴潮水位的影响最为显著,而波致辐射应力与依赖波流相互作用的底应力的影响只在渤海和北黄海相对明显;考虑海浪影响的风暴潮水住过程曲线模拟结果,比不考虑海浪影响的纯风暴潮模拟结果与实测水位曲线吻合的更好,尤其是在减水极值处,其相对误差不超过5.57%. 相似文献
10.
考虑底摩擦的波动折射绕射联合摸式的应用 总被引：3，自引：0，他引：3
本文利用考虑底摩擦的简单波折射绕射联合模式计算了某港附近区域中海浪要素.用本文结果与用简单波折射模式计算所得的结果及与1985年一次台风期间的实际观测资料作比较可以看出,用本文给出的模式算得的海浪要素是合理的,计算结果与实际观测相当好地一致.可以断定,这种模式对于计算复杂海底地形上的近岸波要素是有效的. 相似文献
11.
海洋波浪能平均功率的准确计算是波浪能开发和利用的基础。实践中，波浪能转换装置一般安装在有限水深区域。对于随机波，只有当详尽的波浪谱已知的时候，有限水深区的波能功率才能被准确计算出来。由于种种原因，实践中波浪的实测数据大多以散点图或有义波高和统计波周期的形式给出，而波浪谱信息有时则很难获得。基于这种情况，传统上人们利用无限水深条件下的相关公式来估算有限水深区域的波能功率，但这种做法会造成较大的误差。本研究显示，对于50 m水深的理论波谱JONSWAP谱来说该误差高达14.6%。为了提高波能功率计算的准确性，本文提出了一种基于能量频率的一阶和二阶近似算法，可以在未知波浪谱的情况下较为准确地计算不同水深时的波能功率。针对两种理论波浪谱的计算结果表明，本方法在计算有限带宽内的波能功率时计算误差低于2.8%。 相似文献
12.
The derivation of Green function in a two-layer fluid model has been treated in different ways.In a two-layer fluid with the upper layer having a free surface,there exist two modes of waves propagating due to the free surface and the interface.This paper is concerned with the derivation of Green functions in the three dimensional case of a stationary source oscillating.The source point is located either in the upper or lower part of a two-layer fluid of finite depth.The derivation is carried out by the method of singularities.This method has an advantage in that it involves representing the potential as a sum of singularities or multipoles placed within any structures being present.Furthermore,experience shows that the systems of equations resulted from using a singularity method possess excellent convergence characteristics and only a few equations are needed to obtain accurate numerical results.Validation is done by showing that the derived two-layer Green function can be reduced to that of a single layer of finite depth or that the upper Green function coincides with that of the lower,for each case.The effect of the density on the internal waves is demonstrated.Also,it is shown how the surface and internal wave amplitudes are compared for both the wave modes.The fluid in this case is considered to be inviscid and incompressible and the flow is irrotational. 相似文献
13.
Acoustic scattering of a plane wave incident upon a rough surface over a transition fluid layer within which both the density and sound speed vary with depth is considered. A theory based upon a boundary perturbation method has been applied to a typical seabed environment to study the power spectral density representing the energy distribution of the scattered field over the space. The effects of frequency and roughness properties, including the
roughness height, spatial correlation, and power spectrum, on the power spectral density have been investigated. The results demonstrate that the power spectral density of the scattered field depends upon all the aforementioned parameters, particularly the correlation length and the power spectrum of the rough surface, a conclusion in distinct contrast to the results for the coherent field obtained in an earlier study. It was found that the constituents of the rough surface such as the correlation length and wavenumber spectrum dominate the angular distribution of the scattered energy. These results indicate that it is crucial to employ a suitable topological model in the study of rough seabed scattering. 相似文献
14.
A composite numerical model is presented for computing the wave field in a harbor. The mild slope equation is discretized by a finite element method in the domain concerned. Out of the computational domain, the water depth is assumed to be constant. The boundary element method is applied to the outer boundary for dealing with the infinite boundary condition. Because the model satisfies strictly the infinite boundary condition, more accurate results can be obtained. The model is firstly applied to compute the wave diffraction in a narrow rectangular bay and the wave diffraction from a porous cylinder. The numerical results are compared with the analytical solution, experimental data and other numerical results. Good agreements are obtained. Then the model is applied to computing the wave diffraction in a square harbor with varying water depth. The effects of the water depth in the harbor and the incoming wave direction on the wave height distribution are discussed. 相似文献
15.
A composite numerical model is presented for computing the wave field in a harbor. The mild slope equation is discretized by a finite element method in the domain concerned. Out of the computational domain, the water depth is assumed to be constant. The boundary element method is applied to the outer boundary for dealing with the infinite boundary condition. Because the model satisfies strictly the infinite boundary condition, more accurate results can be obtained. The model is firstly applied to compute the wave diffraction in a narrow rectangular bay and the wave diffraction from a porous cylinder. The numerical results are compared with the analytical solution, experimental data and other numerical results. Good agreements are obtained. Then the model is applied to computing the wave diffraction in a square harbor with varying water depth. The effects of the water depth in the harbor and the incoming wave direction on the wave height distribution are discussed. 相似文献
16.
比例边界有限元法(SBFEM)是一种半解析数值分析的新方法,既融合了有限元法和边界元法的优点,又有其特有的优点。用该方法可求解有限水深下狭缝对双箱水动力作用的影响,为波浪与多浮体超大型结构的相互作用探索一些规律。整个计算域划分成2个无限子域和4个有限子域,并利用加权余量法在各个子域上推导了SBFEM的积分方程;计算了4个数值算例并与边界元等其它数值方法进行了比较,验证了该方法是一种用很少单元便能得到精确结果的高效方法。应用SBFEM对不同箱体宽度、不同狭缝宽度、不同吃水深度条件的双箱作了计算,得出了狭缝对双箱水动力干涉影响的一些规律,对超大型浮体水动力分析和结构设计具有一定的参考价值。 相似文献
17.
The evaluation of seabed response under wave loading is important for prediction of stability of foundations of offshore structures. In this study, a stochastic finite element model which integrates the Karhunen-Loève expansion random field simulation and finite element modeling of wave-induced seabed response is established. The wave-induced oscillatory response in a spatially random heterogeneous porous seabed considering cross-correlated multiple soil properties is investigated. The effects of multiple spatial random soil properties, correlation length and the trend function (the relation of the mean value versus depth) on oscillatory pore water pressure and momentary liquefaction are discussed. The stochastic analyses show that the uncertainty bounds of oscillatory pore water pressure are wider for the case with multiple spatially random soil properties compared with those with the single random soil property. The mean pore water pressure of the stochastic analysis is greater than the one obtained by the deterministic analysis. Therefore, the average momentary liquefaction zone in the stochastic analysis is shallower than the deterministic one. The median of momentary liquefaction depth generally decreases with the increase of vertical correlation length. When the slope of the trend function increases, the uncertainty of pore water pressure is greatly reduced at deeper depth of the seabed. Without considering the trend of soil properties, the wave-induced momentary liquefaction potential may be underestimated. 相似文献
18.
Large Eddy Simulation for Wave Breaking in the Surf Zone 总被引：1，自引：0，他引：1
BAI Yuchuan BAI Yuchuan JIANG Changbo SHEN Huanting 《中国海洋工程》2001,(4):541-552
In this paper, (he large eddy simulation method is used combined with the marker and cell method to study the wave propagation or shoaling and breaking process. As wave propagates into shallow water, the shoaling leads lo the increase of wave height, and then at a certain position, the wave will be breaking. The breaking wave is a powerful agent for generating turbulence, which plays an important role in most of the fluid dynamic processes throughout the surf zone, such as transformation of wave energy, generation of near-shore current and diffusion of materials. So a proper numerical model for describing the turbulence effect is needed. In this paper, a revised Smagorinsky subgrid-scale mode! is used to describe the turbulence effect. The present study reveals that the coefficient of the Smagorinsky model for wave propagation or breaking simulation may be taken as a varying function of the water depth and distance away from the wave breaking point. The large eddy simulation model presented in this pape 相似文献
19.
Wang Liang
Du Heng Lecturer Hohai University Nanjing Engineer Jiangsu Communication Planning Design Institute Nanjing 《中国海洋工程》1993,(1)
- Engineers in coastal engineering have been paying much attention to the research subject on wave breaking. In this paper, previous research results on the calculating methods of wave breaking depth and height are enumerated, the laws of wave transformation before and after wave breaking are investigated, an adequate supposition is made, and the effect of beach slope, bed friction and breaking turbulence on wave breaking is considered. By applying the theory of wave energy dissipation rate and combining with proper formulas of solitary waves, a new calculating formula of wave breaking depth and height on the movable bed is derived and examined with the data from experimental pools of different sizes, and it is proved to be of practicability. 相似文献
20.
Efficient computation of surf zone waves using the nonlinear shallow water equations with non-hydrostatic pressure 总被引：2，自引：0，他引：2
A numerical method for non-hydrostatic, free-surface, irrotational flow governed by the nonlinear shallow water equations including the effects of vertical acceleration is presented at the aim of studying surf zone phenomena. A vertical boundary-fitted grid is used with the water depth divided into a number of layers. A compact finite difference scheme is employed for accurate computation of frequency dispersion requiring a limited vertical resolution and hence, capable of predicting the onset of wave breaking. A novel wet–dry algorithm is applied for a proper handling of moving shoreline. Mass and momentum are strictly conserved at discrete level while the method only dissipates energy in the case of wave breaking. The numerical results are verified with a number of tests and show that the proposed model using two layers without ad-hoc assumptions enables to resolve propagating nonlinear shoaling, breaking waves and wave run-up within the surf and swash zones in an efficient manner. 相似文献