共查询到19条相似文献,搜索用时 125 毫秒
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非均匀水流中非线性波传播的数值模拟 总被引:1,自引:1,他引:1
以一种考虑波流相互作用的新型{Boussinesq}型方程为控制方程组,
采用五阶{Runge}-{Kutta}-{England}格式离散时间积分,采用七点
差分格式离散空间导数,并通过采用恰当的出流边界条件,从而建立了非均匀水流中非线性
波传播的数值模拟模型. 通过对均匀水流与水深水域内和潜堤地形上存在弱流或强流时波浪
传播的数值模拟,说明模型能有效地反映水流对波浪传播的影响. 相似文献
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Boussinesq 类水波模型在港口、海岸以及海洋工程领域应用广泛,但以前对这类模型的变浅性能的研究不够充分. 针对Madsen 和Sch?ffer 提出的一组四阶Boussinesq 方程,从理论和数值两个方面对这一问题进行了探讨. 理论分析了其变浅性能,指出该文献中参数α2 和β2 的取值是不合理的,并重新确定其取值. 在交错网格下建立了基于混合4 阶Adams-Bashforth-Moulton 格式的预报-校正数值模型. 数值模拟了两个典型算例: 一是缓变平坡地形上波浪的传播变形,二是波浪在淹没梯形潜堤上的波浪演化过程. 计算结果分别与解析结果、物理模型实验结果进行了比较,发现变浅系数的取值对数值结果影响很大,新参数比原文参数模拟结果的吻合程度更高,这佐证了理论分析. 相似文献
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从欧拉方程出发,提供了另一种推导完全非线性Boussinesq方程的方法,并对方程的
线性色散关系和线性变浅率进行了改进. 改进后方程的线性色散关系达到了一阶Stokes波
色散关系的Pad\'{e}[4,4]近似,在相对水深达1.0的强色散波浪时仍保持较高的准确性,并且方程的非线性和线性
变浅率都得到了不同程度的改善. 方程的水平一维形式用预估-校正的有限差分格式求解,
建立了一个适合较强非线性波浪的Boussinesq波浪数值模型. 作为验证,模拟了波浪在潜
堤上的传播变形,计算结果和实验数据的比较发现两者符合良好. 相似文献
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变深度浅水域中非定常船波 总被引:1,自引:0,他引:1
以Green—Naghdi(G—N)方程为基础,采用波动方程/有限元法计算船舶经过变深度浅水域时非定常波浪特性.把运动船舶对水面的扰动作为移动压强直接加在Green-Naghdi方程里,以描述运动船体和水面的相互作用.以Series60 CB=0.6船为算例,给出自由面坡高,波浪阻力在船舶经过一个水下凸包时变化规律,并与浅水方程的结果进行了比较.计算结果表明,当船舶经过凸包时,波浪阻力先增加,后减少,并逐渐趋于正常.同时发现,当船速小于临界速度时(Fr=√gh<1.0),G—N方程给出的船后尾波比浅水方程的结果明显,波浪阻力也比浅水方程的结果有所提高,频率散射必须考虑.当船速大于临界速度时(Fr=√gh>1.0),G—N方程的计算结果与浅水方程差别不大,频率散射的影响可以忽略. 相似文献
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基于相平均方法的折射绕射联合波浪模型 总被引:1,自引:0,他引:1
近岸带波浪运动的研究具有很重要的工程意义,近年来已获得了较丰硕的研
究成果并发展了许多波浪模型,而基于不同理论的波浪模型往往具有特定的适用性. 在海岸
工程中应用比较广泛的一类波浪模型以波能(波作用量)守恒为基本依据,如SWAN模型. 该
类模型在实际工程中已经得到了大量的应用,但该类模型未计及波浪绕射效应,成为其突出
的缺陷之一. 如何对模型做适当的改进,使之适用于波浪绕射的模拟,从而在原有基础上拓
广模型的应用范围是一项具有实际意义的研究工作. 该文采用波能(波作用量)守恒方程描
述近岸带波浪运动,通过引入绕射因子,得到折射、绕射联合波浪模型,从而拓广了模型的
应用范围. 通过实际算例验证,表明所建立的模型计及了波浪折射、绕射作用,对相平
均波浪模型在波浪绕射效应模拟方面的改进具有一定的意义. 相似文献
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基于时域高阶边界元方法,建立了完全非线性二维数值波浪水槽,对非周期波浪与直墙的相互作用问题进行了模拟和研究.自由表面满足完全非线性自由水面运动学和动力学边界条件,采用混合欧拉-拉格朗日方法追踪瞬时自由面流体质点,采用四阶Runge-Kutta法对下一时间步的波面和自由面速度势进行更新.采用加速度式法求解直墙表面速度势的时间导数,对瞬时物体湿表面上的水动力压强积分,得到作用在物体上的瞬时波浪力.首先,将全非线性与Serre-Green-Naghdi(SGN)模型的结果进行了对比分析,发现对于大幅值双入射波问题,仅满足弱色散关系的SGN模型大大低估了最大波浪爬高;其次,研究了双入射波与直墙的非线性作用问题,发现线性预报对波浪最大爬高有较大低估,而波浪的非线性成分不只导致了自由面爬高的异常增大,也引起了局部自由面的高频振荡,该物理过程中,直墙所受的波浪载荷,也展示出了与波浪爬高相似的非线性特性;最后,对波浪爬升和波浪力的时间历程进行了频谱分析,发现入射主频波的部分能量传递给了更高频的波浪成分,反映出该问题具有典型的非线性特性. 相似文献
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Waves in deep water with constant vorticity in the region bounded by the free surface and the infinitely deep plane bottom are considered. Using the conformal variables and the conformal transform technique, a system of exact integro-differential equations solved relative to the derivatives with respect to time is derived and the equivalent system of equations is obtained in the Dyachenko variables. The efficiency of using the obtained system in the Dyachenko variables for investigating surface wave dynamics on the current of infinite depth with constant vorticity is demonstrated with reference to numerical experiments. 相似文献
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Boussinesq 类水波模型在港口、海岸以及海洋工程领域应用广泛,但以前对这类模型的变浅性能的研究不够充分. 针对Madsen 和Schäffer 提出的一组四阶Boussinesq 方程,从理论和数值两个方面对这一问题进行了探讨. 理论分析了其变浅性能,指出该文献中参数α2 和β2 的取值是不合理的,并重新确定其取值. 在交错网格下建立了基于混合4 阶Adams-Bashforth-Moulton 格式的预报-校正数值模型. 数值模拟了两个典型算例: 一是缓变平坡地形上波浪的传播变形,二是波浪在淹没梯形潜堤上的波浪演化过程. 计算结果分别与解析结果、物理模型实验结果进行了比较,发现变浅系数的取值对数值结果影响很大,新参数比原文参数模拟结果的吻合程度更高,这佐证了理论分析. 相似文献
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Higher order Boussinesq-type equations for wave propagation over variable bathymetry were derived. The time dependent free surface boundary conditions were used to compute the change of the free surface in time domain. The free surface velocities and the bottom velocities were connected by the exact solution of the Laplace equation. Taking the velocities on half relative water depth as the fundamental unknowns, terms relating to the gradient of the water depth were retained in the inverse series expansion of the exact solution, with which the problem was closed. With enhancements of the finite order Taylor expansion for the velocity field, the application range of the present model was extended to the slope bottom which is not so mild. For linear properties, some validation computations of linear shoaling and Booij' s tests were carried out. The problems of wave-current interactions were also studied numerically to test the performance of the enhanced Boussinesq equations associated with the effect of currents. All these computational results confirm perfectly to the theoretical solution as well as other numerical solutions of the full potential problem available. 相似文献
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A hybrid scheme composed of finite‐volume and finite‐difference methods is introduced for the solution of the Boussinesq equations. While the finite‐volume method with a Riemann solver is applied to the conservative part of the equations, the higher‐order Boussinesq terms are discretized using the finite‐difference scheme. Fourth‐order accuracy in space for the finite‐volume solution is achieved using the MUSCL‐TVD scheme. Within this, four limiters have been tested, of which van‐Leer limiter is found to be the most suitable. The Adams–Basforth third‐order predictor and Adams–Moulton fourth‐order corrector methods are used to obtain fourth‐order accuracy in time. A recently introduced surface gradient technique is employed for the treatment of the bottom slope. A new model ‘HYWAVE’, based on this hybrid solution, has been applied to a number of wave propagation examples, most of which are taken from previous studies. Examples include sinusoidal waves and bi‐chromatic wave propagation in deep water, sinusoidal wave propagation in shallow water and sinusoidal wave propagation from deep to shallow water demonstrating the linear shoaling properties of the model. Finally, sinusoidal wave propagation over a bar is simulated. The results are in good agreement with the theoretical expectations and published experimental results. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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A σ‐coordinate non‐hydrostatic model, combined with the embedded Boussinesq‐type‐like equations, a reference velocity, and an adapted top‐layer control, is developed to study the evolution of deep‐water waves. The advantage of using the Boussinesq‐type‐like equations with the reference velocity is to provide an analytical‐based non‐hydrostatic pressure distribution at the top‐layer and to optimize wave dispersion property. The σ‐based non‐hydrostatic model naturally tackles the so‐called overshooting issue in the case of non‐linear steep waves. Efficiency and accuracy of this non‐hydrostatic model in terms of wave dispersion and nonlinearity are critically examined. Overall results show that the newly developed model using a few layers is capable of resolving the evolution of non‐linear deep‐water wave groups. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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The dependence of the velocity of the motion of a tow with an inclined plate mounted in a wave water channel on the wave parameters,
the submergence depth, and the angle of inclination and dimensions of the plate is experimentally investigated. The effect
of tow motion counter to the waves is detected and theoretically justified. The free surface profiles for periodic waves above
an inclined plate obtained using the elolutionary system of the Boussinesq approximation equations correspond to the measured
ones. The pulse generated as a result of wave breakup is estimated. 相似文献
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A novel approach that embeds the Boussinesq‐type like equations into an implicit non‐hydrostatic model (NHM) is developed. Instead of using an integration approach, Boussinesq‐type like equations with a reference velocity under a virtual grid system are introduced to analytically obtain an analytical form of pressure distribution at the top layer. To determine the size of vertical layers in the model, a top‐layer control technique is proposed and the reference location is employed to optimize linear wave dispersion property. The efficiency and accuracy of this NHM with Boussinesq‐type like equations (NHM‐BTE) are critically examined through four free‐surface wave examples. Overall model results show that NHM‐BTE using only two vertical layers is capable of accurately simulating highly dispersive wave motion and wave transformation over irregular bathymetry. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Flexural gravity wave scattering by multiple articulated floating elastic plates is investigated in the three cases for water of finite depth, infinite depth and shallow water approximation under the assumptions of two-dimensional linearized theory of water waves. The elastic plates are joined through connectors, which act as articulated joints. In the case when two semi-infinite plates are connected through a single articulation, using the symmetric characteristic of the plate geometry and the expansion formulae for wave-structure interaction problem, the velocity potentials are obtained in closed forms in the case of finite and infinite water depths. On the other hand, in the case of shallow water approximation, the continuity of energy and mass flux are used to obtain a system of equations for the determination of the full velocity potentials for wave scattering by multiple articulations. Further, using the results for single articulation and assuming that the articulated joints are wide apart, the wide-spacing approximation method is used to obtain the reflection coefficient for wave scattering due to multiple articulated floating elastic plates. The effects of the stiffness of the connectors, length of the elastic plates and water depth on the propagation of flexural gravity waves are investigated by analysing the reflection coefficient. 相似文献
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促进其线性频散特征另一种形式的Bousinesq方程 总被引:1,自引:0,他引:1
Bousinesq方程能够用于模拟表面重力波传播过程中的折射、绕射、反射以及浅化,非线性作用等现象.用不同垂直积分方法所得到的二维Boussinesq方程形式具有不同的线性频散特征.采用两个不同的水深层的水平速度变量组合,推导出一个新形式的Bousinesq方程.通过对其参数的设置可得到精确的线性频散解Pade近似4阶精度.其适用范围已由原来的浅水,向深水拓进.相速误差小于2%,其拓展适用范围可达到08个波长水深.应用所得到的新型Bousinesq方程,采用有限差分法,对经典工况进行了数值模拟,其计算结果表明,计算值与物模实验值吻合较好.这说明本文新形式的Boussinesq方程对变水深非线性效应所产生的能量频散有着较为精确的描述 相似文献