海浪感应电磁场的理论计算   总被引：4，自引：0，他引：4  

张自力  魏文博  刘保华  邓明  金胜 《海洋学报》2008,30(1):42-46

根据麦克斯韦电磁理论,在地磁场中运动的海水将产生感应电磁场。利用一个简单的数学物理模型对感应电磁场在海水内部的分布进行了计算,结果表明海浪产生的电磁场明显依赖于海浪波动的周期及浪高。在100 m的海水深度内,海浪产生的磁感应强度的大小为纳特数量级,而电场强度的大小为几个微伏每米。在同一海水深度处,磁感应强度随海水波动的周期呈现近线性变化,而电场强度的大小有一个极值,该极值随海水深度的增加向长周期方向移动。海浪产生的电磁场是影响海洋电磁探测数据精度的主要噪声之一。  相似文献   

Alternative forms of the higher-order Boussinesq equations: Derivations and validations   总被引：2，自引：0，他引：2  

Z.L. Zou  K.Z. Fang 《Coastal Engineering》2008

An alternative form of the Boussinesq equations is developed, creating a model which is fully nonlinear up to O(μ⁴) (μ is the ratio of water depth to wavelength) and has dispersion accurate to the Padé [4,4] approximation. No limitation is imposed on the bottom slope; the variable distance between free surface and sea bottom is accounted for by a σ-transformation. Two reduced forms of the model are also presented, which simplify O(μ⁴) terms using the assumption ε = O(μ^2/3) (ε is the ratio of wave height to water depth). These can be seen as extensions of Serre's equations, with dispersions given by the Padé [2,2] and Padé [4,4] approximations. The third-order nonlinear characteristics of these three models are discussed using Fourier analysis, and compared to other high-order formulations of the Boussinesq equations. The models are validated against experimental measurements of wave propagation over a submerged breakwater. Finally, the nonlinear evolution of wave groups along a horizontal flume is simulated and compared to experimental data in order to investigate the effects of the amplitude dispersion and the four-wave resonant interaction.  相似文献   

Recent Advancement in Modeling Seafloor Dissipative Mechanism in Shallow Water     

Philip L.-F.LIU  Yong Sung PARK 《中国海洋工程》2008,22(1):1-10

In this paper, the recent development in modeling seabed dissipative mechanisms in shallow water is reviewed. Specifically, laminar and turbulent boundary layer solutions as well as viscous mud flow solutions under transient waves are presented. These analytical solutions are compared with experimental data for both solitary waves and cnoidal waves. Very goed agreement is ohtained. The Boussinesq equations with boundary layer effects and the muddy seabed effects are also shown.  相似文献   

Hyperbolic Mild Slope Equations with Inclusion of Amplitude Dispersion Effect: Random Waves     

ZOU Zhi-li  JIN Hong 《中国海洋工程》2008,22(4)

New hyperbolic mild slope equations for random waves are developed with the inclusion of amplitude dispersion. The frequency perturbation around the peak frequency of random waves is adopted to extend the equations for regular waves to random waves. The nonlinear effect of amplitude dispersion is incorporated approximately into the model by only considering the nonlinear effect on the carrier waves of random waves, which is done by introducing a representative wave amplitude for the carrier waves. The computation time is greatly saved by the introduction of the representative wave amplitude. The extension of the present model to breaking waves is also considered in order to apply the new equations to surf zone. The model is validated for random waves propagate over a shoal and in surf zone against measurements.  相似文献   

Simulation of Random Waves and Associated Laminar Bottom Shear Stresses     

Mao-Lin SHEN  Ching-Jer HUANG 《中国海洋工程》2008,22(3):477-490

This work presents a new approach for simulating the random waves in viscous fluids and the associated bottom shear stresses. By generating the incident random waves in a numerical wave flume and solving the unsteady two-dimensional Navier-Stokes equations and the fully nonlinear free surface boundaiy conditions for the fluid flows in the flume, the viscous flows and laminar bottom shear stresses induced by random waves axe determined. The deterministic spectral amplitude method implemented by use of the fast Fourier transform algorithm was adopted to generate the incident random waves. The accuracy of the numerical scheme is confirmed by comparing the predicted wave spectrum with the target spectrum and by comparing the nanlerical transfer function between the shear stress and the surface elevation with the theoretical transfer function. The maximum bottom shear stress caused by random waves, computed by this wave model, is compared with that obtained by Myrhaug＇ s model （1995）. The transfer function method is also employed to determine the maximum shear stress, and is proved accurate.  相似文献   

Finite volume scheme for the solution of 2D extended Boussinesq equations in the surf zone   总被引：2，自引：0，他引：2  

Mara Tonelli  Marco Petti 《Ocean Engineering》2010,37(7):567-582

In this paper, a hybrid finite volume-finite difference scheme is applied to study surf zone dynamics. The numerical model solves the 2DH extended Boussinesq equations proposed by Madsen and Sørensen (1992) where nonlinear and dispersive effects are both relevant whereas it solves NSWE equations where nonlinearity prevails. The shock-capturing features of the finite volume method allow an intrinsic representation of wave breaking and runup; therefore no empirical (calibration) parameters are necessary. Comparison with laboratory measurements demonstrates that the proposed model can accurately predict wave height decay and mean water level setup, for both regular and solitary wave breaking on a sloping beach. The model is also applied to reproduce two-dimensional wave transformation and breaking over a submerged circular shoal, showing good agreement with experimental data.  相似文献   

Shock-capturing Boussinesq-type model for nearshore wave processes     

Volker Roeber  Kwok Fai Cheung  Marcelo H. Kobayashi 《Coastal Engineering》2010

This paper describes the formulation and validation of a nearshore wave model for tropical coastal environment. The governing Boussinesq-type equations include the conservative form of the nonlinear shallow-water equations for shock capturing. A Riemann solver supplies the inter-cell flux and bathymetry source term, while a Godunov-type scheme integrates the evolution variables in time. The model handles wave breaking through momentum conservation with energy dissipation based on an eddy viscosity concept. The computed results show very good agreement with laboratory data for wave propagation over a submerged bar, wave breaking and runup on plane beaches as well as wave transformation over fringing reefs. The model accurately describes transition between supercritical and subcritical flows as well as development of dispersive waves in the processes.  相似文献   

Numerical implementation and sensitivity analysis of a wave energy converter in a time-dependent mild-slope equation model     

Charlotte Beels  Peter Troch  Griet De Backer  Marc Vantorre  Julien De Rouck 《Coastal Engineering》2010

Several Wave Energy Converters (abbreviated as WECs) have intensively been studied and developed during the last decade and currently small farms of WECs are getting installed. WECs in a farm are partly absorbing, partly redistributing the incident wave power. Consequently, the power absorption of each individual WEC in a farm is affected by its neighbouring WECs. The knowledge of the wave climate around the WEC is needed to predict its performance in the farm. In this paper a technique is developed to implement a single and multiple WECs based on the overtopping principle in a time-dependent mild-slope equation model. So far, the mild-slope equations have been widely used to study wave transformations around coastal and offshore structures, such as breakwaters, piles of windmills and offshore platforms. First the limitations of the WEC implementation are discussed through a sensitivity analysis. Next the developed approach is applied to study the wave height reduction behind a single WEC and a farm. The wake behind an isolated WEC is investigated for uni- and multidirectional waves; it is observed that an increase of the directional spread leads to a faster wave redistribution behind the WEC. Further the wake in the lee of multiple WECs is calculated for two different farm lay-outs, i.e. an aligned grid and a staggered grid, by adapting the performance of each WEC to its incident wave power. The evolved technique is a fast tool to find the optimal lay-out of WECs in a farm and to study the possible influence on surrounding activities in the sea.  相似文献   

波浪和风生浪流作用下的近岸海底泥沙运移模型的推广和应用   总被引：1，自引：0，他引：1       下载免费PDF全文

邹舒觅  林缅 《地球物理学进展》2007,22(1):273-278

本文利用数值计算和经验公式相结合的方法,获得了在波浪和风生流和波浪共同作用下海底泥沙输移的二维模型.在此基础上,讨论了海底泥沙输移在风速、风向和泥沙粒径不同等三种情况下的变化特征;指出了经验公式对泥沙输移规律的适用范围以及风速、风向对于近岸处泥沙输移重要性.这一研究结果对近岸结构物的选址设计具有实际应用价值.  相似文献   

二维界面流的稳定性及相路方程的椭圆型条件          下载免费PDF全文

欧阳首承  朱克云 《大气科学》1991,15(1):74-83

针对天气实践的一些问题,本文改变了文献[1]的某些作法,分别就上、下行波的稳定性情况,切变邻近区域相路方程的类型条件作了较细致的讨论。结果表明:不稳定极易发生在背急流方向而立的左侧,并在不连续界面的两侧其稳定性是不同的,其相路方程也是有条件的——急流轴及其左侧邻近地区,一般满足椭圆型条件,而其右侧则有可能出现双曲型,从而揭示了扰动沿东西向传播时不稳定易于维持的原因,并与天气实践吻合。  相似文献