三维物体上二阶波浪绕射的实时模拟

采用二阶时域理论对非线性波浪在任意三维物体周围的绕射问题进行了研究，对自由表面边界条件进行Taylor级数展开，应用摄动展开可以建立相应的边值问题，而且此边值问题的计算域不随时间变化，运用基于B－样条的边界元方法求解每一时刻的波浪场，二阶自由表面边界条件在时间上进行数值积分，在自由表面加了一个人工阻尼层以避免波浪的反射，速度势分解为已知的入射势和未知的散射势，初始条件采用二阶Stokes波浪场，通过加入物体表面边界条件，得到散射势在时间和空间上的发展，本文对圆柱所受规则波的二阶波浪力和波浪爬高进行了计算，数值结果表明此理论计算准确，效率高，数值稳定。     

二维水波辐射问题的二阶时域解

用二阶理论在时域范围内研究二维二阶非线性水波的辐射问题,一阶、二阶问题分别满足各自的自由表面条件和物面条件,采用人工阻尼来吸收反射波.计算采用有限元法,对水平半圆柱体在水面的振荡问题进行了计算,计算了波高时间历程和水动力,计算结果与有关文献中的数据相比符合较好.     

多向不规则波绕射的数值模拟

采用有限元求解Ｂｏｕｓｓｉｎｅｓｑ方程数值计算模型,对单突堤和双突堤的波浪绕射进行了数值模拟,并与物模试验进行对比验证。模拟结果表明入射波浪的方向分布对波浪的绕射具有明显的影响,使防波堤后的波浪增大,开阔区域的浪浪减小,波浪的方向分布对港内波浪的分布具有一定的均化作用。     

变深区浅水波的绕射和折射计算

本文开发了基于射线理论的浅水波计算程序,提出了一种解决射线相交的简便方法.应用非线性长波方程,以波浪对圆柱形人工岛和海凹的绕射、折射及对坡岸的斜向入射为例,进行了数值计算.在变深区的开边界处,利用射线理论给定入射波,获得了与实际观测相吻合的结果.     

水下圆形浅滩附近波浪绕射的计算

采用波数矢量无旋和波能守恒方程对圆形浅滩附近水域波浪绕射进行了数值计算,计算模型中采用Ｂａｔｔｊｅｓ关系与波数矢量无旋,波能量守恒方程一起联合求解圆形浅滩附近水域波浪折射影响下的波浪要素。本文的数值计算模型对圆形浅滩水域波浪折射绕射现象的验证结果表明,计算所得结果与试验结果是吻合的,数学模型是可靠和合理的,具有实用价值。     

波浪对直墙前垂直圆柱的绕射

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。     

用时域法求解二维二阶非线性水波

本文用二阶理论在时域范围内计算二维二阶非线性水波,一、二阶问题分别满足各自的自由表面条件和物面条件,流场内的速度势通过求解有限元方程得到,计算采用八结点四边形等参单元,采用人工阻尼来吸收反射波,对楔形体在水面上的振荡问题进行了计算,计算结果与有关文献相比符合较好。     

有限水深二维绕射问题的二阶速度势和水动力

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     

双层直立圆弧型防波堤上绕射波浪力的解析计算

基于微幅波绕射理论,应用特征函数展开法,推导了双层直立圆弧型透空防波堤的波浪绕射解析解,从而将已有的比例边界有限元法拓展为解析算法,并据此对外层与内层防波堤所受波浪载荷进行了解析计算。计算结果表明:应用本文方法对直立透空圆环柱的绕射波浪载荷进行验证计算,所得结果与现有的解析解完全吻合,说明方法可靠。双层堤较单层堤能更有效地减弱波浪作用。波浪的入射角度和特征参数、防波堤张角与半径、防波堤透空系数以及水深等因素的相对变化对双层堤的波浪作用均存在一定影响。     

海浪能量方向分布形式对近岸波折绕射计算的影响

本文考虑海浪能量在方向上的分布，结合组成波折绕射控制方程组，建立了海浪方向谱的折绕射联合模型，并在简单地形上实施数值计算，比较简单波及折绕射的计算结果，表明：考虑海浪能量的方向分布，能减弱波动能量辐聚、辐散的程序，改变辐聚、辐散的位置。     

On the distribution of second order pressure on a vertical circular cylinder

This 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.     

A composite numerical model for wave diffraction in a harbor with varying water depth

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.     

A composite numerical model for wave diffraction in a harbor with varying water depth

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.     

层化海洋中的二阶波散射作用问题

引入Stokes有限振幅水波的多色波作用机制 ,采用二层层化海洋模型 ,分析了层化海洋中非线性波对结构的散射作用问题。提出了二层海洋中二阶水波散射条件的数学表达式 ,进而推导了二层海洋中二阶波对一般型圆柱散射作用的格林积分解式 ,并给出了对解式中自由面及分层界面无限积分的递推算式。     

浅水浮式生产储油系统(FPSO)二阶定常力数值仿真研究

应用三维线性势流理论和Ir J A Pinkster的近场分析方法,对超大型浮式生产储油系统(32万吨FPSO)的二阶波浪定常力进行了数值仿真分析,研究浅水情况下,不同水深对FPSO受到二阶波浪定常力的影响,对浅水油田中FPSO的设计应用有一定的实用意义。     

深水平台二阶波浪力研究综述

回顾了近几年来深海平台二阶波浪力的研究成果。对几种典型深海平台结构二阶波浪力研究作了详细的阐述,包括理论分析、数值计算和实验验证等。最后指出目前该领域主要研究方向,作为进一步研究的参考。     

A second order random wave model for predicting the power performances of a wave energy converter

The power performances of a point absorber wave energy converter(WEC) operating in a nonlinear multidirectional random sea are rigorously investigated. The absorbed power of the WEC Power-Take-Off system has been predicted by incorporating a second order random wave model into a nonlinear dynamic filter. This is a new approach, and, as the second order random wave model can be utilized to accurately simulate the nonlinear waves in an irregular sea, avoids the inaccuracies resulting from using a first order linear wave model in the simulation process. The predicted results have been systematically analyzed and compared, and the advantages of using this new approach have been convincingly substantiated.