共查询到19条相似文献，搜索用时 97 毫秒
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波浪对直墙前垂直圆柱的绕射 总被引：1，自引：2，他引：1
应用映像原理，将直墙前单个圆柱对波浪的绕射问题，变换为双柱对双向波浪的绕射问题，应用速度势的特征展开方法，建立了直墙前垂直圆柱对波浪绕射的解析解。通过数值计算研究了圆柱与直墙间距离大小、波浪入射角等因素对圆柱上总波浪作用力的影响。计算结果表明，直墙前圆柱上的波浪力将成倍地增加，且随着波数的变化而发生振荡。 相似文献
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波浪对透空外双壁筒柱的绕射 总被引：3，自引：2，他引：3
应用透空壁内流体速度与两壁间压力差成正比的线性模型，建立了外壁透空的双筒圆柱对波浪绕射的解析解。通过数值计算研究了外壁透空率的大小、内外柱半径之比等因素对桩柱上总波浪作用力和波面高度的影响。数值结果表明圆柱外壁透空系数的增加，将明显地降低圆柱周围的波浪高度和圆柱上的波浪力；内外柱径之比的大小对波浪力和波高的最大值无太大影响，而对波浪力剧烈衰减区的位置和波高的振荡周期有决定作用。 相似文献
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本文给出有限水深二维物体二阶绕射势在外域中的解析表达式，从而准确满足二阶绕射势的辐射条件。二阶绕射势在内域自由表面上的边界条件则由一阶势的数值微分求得。然后对内域用简单Ｇｒｅｅｎ函数法求得二阶绕射势。本文对二维浮体和潜体在不同水深和潜深情况下的绕射问题进行了计算，求得了二阶绕射势和二阶定常及倍频波浪力。讨论了水深和潜深对波浪力的影响以及二阶绕射势对非线性波浪力的贡献 相似文献
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《海洋科学进展》2004,22(4):i001-i002
第 1 期全球大洋环流诊断模式研究———流场及流函数魏泽勋 ,乔方利 ,方国洪 ,崔秉昊 ,方 越 ,王新怡 (1)…………………………海浪谱峰周期与跨零周期的一个经验关系方式华 锋 ,范 斌 ,卢 燕 ,王俊勤 (16)……………………………………………黄河口二维潮波泥沙有限元数学模型及应用 (Ⅰ )———模型及其验证李东风 ,程义吉 ,邹 冰 ,张红武 ,韩巧兰 (2 1)…………正交直墙前直立圆柱的波浪绕射的解析研究宁德志 ,滕 斌 ,宋向群 (2 9)………………………………………………………不同波峰定义对波峰统计特征值的影响张寒元 ,于定… 相似文献
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基于局部冲刷研究的大型圆柱周围波浪特性分析 总被引：2，自引：0，他引：2
波浪环境下,大型圆柱的存在改变了周围原有波浪条件,直接导致局部冲刷。利用MacCamy和Fuchs的绕射理论对相对柱径较大(0.15相似文献
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为研究人工岛尺度变化和波浪方向分布对人工岛绕射波浪的影响,基于MIKE21-BW模型应用数值方法模拟人工岛波浪绕射过程。数值结果与Briggs等的物理试验结果的对比表明两者吻合较好,验证了模型的适用性。在规则波条件时,圆形人工岛绕射波浪的数值结果与线性波浪绕射理论解基本一致;采用该模型分别模拟了6种尺度的圆形人工岛、单向不规则波和9种方向分布θ_(max)、4种谱峰周期条件时绕射波浪分布情况。分析结果表明,圆形人工岛绕射系数随着尺度的增加,掩护区绕射系数随之减小;θ_(max)在10°~45°范围内,随着θmax的增大,绕射系数随之增大,θ_(max)在45°~75°内绕射系数变化较小;随着谱峰周期的增加,绕射系数随之增大。研究成果既为相关规范的完善提供了基础,也为相关工程设计提供了参考。 相似文献
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本文用有限元法配合时步处理来求解三维非线性水波的绕射问题,自由表面条件和物面条件都满足到二阶,采用人工阻尼区来吸收反射波,流场内的速度势通过求解有限元方程得到。对垂直圆柱体的绕射问题进行了计算,得到了自由表面波高时间历程和圆柱所受到的波浪力,计算结果和有关文献的理论计算结果进行了比较。 相似文献
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In this paper, the principle of mirror image is used to transform the problem of wave diffraction from a circular cylinder in front of orthogonal vertical walls into the problem of diffraction of four symmetric incident waves from four symmetrically arranged circular cylinders, and then the eigenfunction expansion of velocity potential and Grafs addition theorem are used to give the analytical solution to the wave diffraction problem. The relation of the total wave force on cylinder to the distance between the cylinder and orthogonal vertical walls and the incidence angle of wave is also studied by numerical computation. 相似文献
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Qiu Dahong 《中国海洋工程》1992,(2)
Based on the 1st order cnoidal wave theory, the nonlinear wave diffraction around a circular cylinder in shallow water is studied in this paper. The equation of the wave surface around the cylinder is formulated and by using this formula the wave surface elevation on the cylinder surface can be obtained. In this paper, the formula for calculating the cnoidal wave force on a circular cylinder is also derived. For the wave conditions which are often encountered in practical engineering designs, the ratios of the nonlinear wave forces to the linear wave forces are calculated, and the results are plotted in this paper for design purposes. In order to verify the theoretical results, model tests are conducted. After comparing the test results with the theoretical ones, it is concluded that, in shallow water, for the case of T g / d~(1/2) > 8-10 and H / d > 0.3, the cnoidal wave theory should be used to calculate the wave action on a cylindrical pier. 相似文献
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The interaction of a solitary wave with an array of surface-piercing vertical circular cylinders is investigated numerically. The wave motion is modeled by a set of generalized Boussinesq equations. The governing equations are discretized using a finite element method. The numerical model is validated against the experimental data of solitary wave reflection from a vertical wall and solitary wave scattering by a vertical circular cylinder respectively. The predicted wave surface elevation and the wave forces on the cylinder agree well with the experimental data. The numerical model is then employed to study solitary wave scattering by arrays of two circular cylinders and four circular cylinders respectively. The effect of wave direction on the wave forces and the wave runup on the cylinders is quantified. 相似文献
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R. Eatock Taylor
S. M. Hung
F. P. Chau
《Applied Ocean Research》1989,11(4):183-193This paper shows how the second order wave pressure on the submerged surface of a body may be obtained without solving the boundary value problem for the second order velocity potential. The corresponding analytical solution for a vertical circular cylinder is developed, and selected results are presented which illustrate a number of novel phenomena not occurring in first order diffraction analysis. 相似文献
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Numerical calculation of forces induced by short-crested waves on a vertical cylinder of arbitrary cross-section 总被引：1，自引：0，他引：1
Most off-shore oil platforms are supported by vertical cylinders extending to the ocean floor. An important problem in off-shore engineering is the calculation of the wave loading exerted on these vertical cylinders. Analytical solutions have been found for the case of plane incident waves incident on a circular cylinder by MacCamy and Fuchs [(1954), Wave forces on piles: a diffraction theory. U.S. Army Corps of Engineering, Beach Erosion Board, Technical Memorandum No. 69] and also for short-crested waves incident on a circular cylinder by Zhu [(1993), Diffraction of short-crested waves around a circular cylinder. Ocean Engng 20, 389–407]. However, for a cylinder of arbitrary cross-section, no analytic solutions currently exist. Au and Brebbia [(1983), Diffraction of water waves for vertical cylinders using boundary elements. Appl. Math. Modelling 7, 106–114] proposed an efficient numerical approach to calculate the wave loads induced by plane waves on vertical cylinders by using the boundary element method. However, wind-generated waves are better modelled by short-crested waves. Whether or not these short-crested waves can induce larger wave forces on a structure is of great concern to ocean engineers. In this paper wave loads, induced by short-crested incident waves, on a vertical cylinder of arbitrary cross-section are discussed. For a cylinder of certain cross-section, the wave loads induced by short-crested waves can be larger than those induced by plane waves with the same total wave number. 相似文献
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—Based on a linear model of the pressure difference between two sides of a porous wall and thefluid velocity inside it.an analytic solution is established for wave diffraction from a cylinder with an outerporous column and an inner solid column.Numerical experiments are carried out to examine the effects ofthe wave force on a porous low-column cylinder and the wave elevations outside and inside the cylinderdue to the porous character of the outer column and the ratio between the radii of the inner and outer col-umns.The numerical results show that the increase in the coefficient of porosity of the outer column of adouble column cylinder will reduce the wave elevation around the cylinder and the wave load on it.The ra-dius of the inner column does not affect too much the wave elevation around the cylinder and the totalforce on the cylinder. 相似文献
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A numerical model for coastal water wave motion that includes an effective method for treatment of non-reflecting boundaries is presented. The second-order one-way wave equation to approximate the non-reflecting boundary condition is found to be excellent and it ensures a very low level of reflection for waves approaching the boundary at a fairly wide range of the incidence angle. If the Newman approximation is adopted, the resulting boundary condition has a unique property to allow the free propagation of wave components along the boundary. The study is also based on a newly derived mild-slope wave equation system that can be easily made compatible to the one-way wave equation. The equation system is theoretically more accurate than the previous equations in terms of the mild-slope assumption. The finite difference method defined on a staggered grid is employed to solve the basic equations and to implement the non-reflecting boundary condition. For verification, the numerical model is then applied to three coastal water wave problems including the classical problem of plane wave diffraction by a vertical circular cylinder, the problem of combined wave diffraction and refraction over a submerged hump in the open sea, and the wave deformation around a detached breakwater. In all cases, the numerical results are demonstrated to agree very well with the relevant analytical solutions or with experimental data. It is thus concluded that the numerical model proposed in this study is effective and advantageous. 相似文献
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A time-domain higher-order boundary element scheme was utilized to simulate the linear and nonlinear irregular waves and diffractions due to a structure. Upon the second-order irregular waves with four Airy wave components being fed through the inflow boundary, the fully nonlinear boundary problem was solved in a time-marching scheme. The open boundary was modeled by combining an absorbing beach and the stretching technique. The proposed numerical scheme was verified by simulating the linear regular and irregular waves. The scheme was further applied to compute the linear and nonlinear irregular wave diffraction forces acting on a vertical truncated circular cylinder. The nonlinear results were also verified by checking the accuracy of the nonlinear simulation. 相似文献