【作者】 孙哲；

【导师】 庞永杰；

【作者基本信息】 哈尔滨工程大学 ， 流体力学， 2012， 硕士

【摘要】 对波浪环境的实验和数值模拟是船舶与海洋工程领域的重要课题，计算机技术的飞速发展使得用数值模拟的方法代替部分的水池实验成为可能，进而形成了一门所谓“数值波浪水池”技术。本文针对该项技术的二维情形作了以下研究：利用MATLAB软件，基于边界元法和混合欧拉拉格朗日（MEL）方法编制了二维数值波浪水池程序。波浪生成采用仿物理的形式（摇板和推板）。自由面的更新采用一种显示的二阶Taylor展开方法，其几何形状采用将横纵坐标分别使用三次样条曲线拟合的方式逼近。为了解决边界上分布源和分布偶极的积分奇性问题，分别采用了一种特殊的Gauss型积分公式和一种将对数函数的法向导数转化为角度对弧长导数的变量替换方法。自由面与刚性边界的处的“角点”问题采用“二重节点”技术处理。消波方法采用布置人工阻尼层的方法来实现。为检验模型的性能，作者利用该模型计算了多种不同类型的波浪，包括二阶Stokes波、不规则波（P-M谱）、孤立波、瞬态极限波和瞬态聚焦波。数值计算结果表明：在造波板做大幅、较高频率或有突变的运动时，该模型能够稳定的进行较长时间的模拟。模拟的结果与相关理论解吻合的很好。在不同的节点密度和不同的计算时间步长的条件下的模拟表明，该模型的收敛速度和精度是令人满意的。为了研究粘性作用对波浪传播过程中的衰减的影响，本文又以FLUENT软件为平台，按照哈尔滨工程大学综合实验水池的物理尺度和造波形式建立了一个粘性数值波浪水池。采用结构化的动网格技术模拟摇板造波。通过在池尾布置阻尼消波区来消除反射波的影响。通过大范围的规则波模拟（圆频率ω=5.5rad/s～1.8rad/s，波高H=0.1m~0.4m）发现，波浪的沿程衰减可用对数规律加以拟合，进而得到了适用于一定参数范围的相关拟合系数。利用所建立的粘性数值波浪水池模型，作者对二维情况下的主动吸收式造波技术进行了研究，应用所谓“频域”方法给出带有吸波功能的传递函数，数值仿真结果表明，该模型基本实现了主动吸收式造波功能。更多还原

【Abstract】 The simulation of wave environment by experiment or numerical method is an essential topic in thefield of Naval Architecture and Ocean Engineering. The fast development of modern computer science hasempowered the researchers to, at least partly, substitute numerical simulation for experiment study, whichis called Numerical Wave Tanks (NWT) technique. Some fundamental research has been conducted in twodimensional situation:A two dimensional NWT was developed based in Boundary Element Method (BEM) and MixedEulerian-Lagrangian (MEL) method, using MATLAB software. The wave-maker is piston-type orflap-type. The free surface is updated by an explicit2ndorder truncated Taylor expansion formula, and itsshape is approached by fitting the x and y coordinates using3rdsipline separately. In order to manipulatethe integration singularity, two corresponding techniques were adopted. Specially, A Gauss type quadraturewas employed in the calculation of singular source distribution integration, and the normal derivative oflogarithmic function was changed into the derivative of an angle to remove the singularity of dipoledistribution integration. The so-called “corner problem” which occurred at the interaction point of the freesurface and rigid boundaries was manipulated by double node method. The artificial damping zone wasused to avoid wave reflecting.In order to test the performance of the NWT, a variety of waves were simulated, including2ndorderStokes waves, irregular wave (P-M spectrum), solitary wave, transient overtopping wave and transientfocus wave. The numerical results show that this NWT can work steadily for quite a long time even whenthe wave-maker moves rapidly, high-frequency or sharply. And the numerical results also mach thecorresponding analytical results well in all the simulated cases. The convergence rate is good according thecalculation with different node density and time intervals.With the CFD software FLUENT, a viscous NWT was established to investigate the attenuationfeature the wave propagation. This dimension of the viscous NWT was chosen according to the physicaldimension of the general deepwater basin. Structural and dynamic mesh technique was adopted to ensurethe fluent movement of the rocker. At the end of the basin, an artificial damping zone was distributed toabsorb the incident wave.After simulating a wide range of regular wave (ω=5.5rad/s～1.8rad/s, H=0.1m~0.4m), the waveattenuation character can be represented by logarithmic function. And the corresponding coefficients werealso obtained.The Active Reflection Compensating (ARC) Technique was investigated by this viscous NWT. Thesystem transformation function was obtained by using the so-called “frequency domain” method. Thenumerical simulation indicate that this function works well i.e. the re-reflecting wave was absorbedeffectively.更多还原