【作者】 王海龙；

【导师】 邹志利；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2010， 硕士

【摘要】 非线性波浪对海上建筑物作用的时域计算是目前海洋工程中的一个重要课题。采用耦合计算模型可以发挥Boussinesq方程能够计算复杂地形、三维有限元势流模型可以适合复杂边界的优点。本文研究将时域三维耦合计算模型应用于计算边界较为复杂的海洋建筑物的波浪场的计算上。计算模型将计算域分为内域和外域：内域为包围模型的矩形区域,采用三维Laplace方程,用有限元方法求解；外域为内域外面到四周边界的水域,采用水平二维Boussinesq方程,用有限差分法求解。两域在交界面处相耦合。首先,介绍了通用有限元分析软件ANSYS的网格生成技术并将其应用在圆柱模型和船体模型的内域网格的划分中。其次,将三维耦合计算模型应用于计算圆柱物体上的非线性波浪压力和流场波面升高,并简要介绍了相关的模型实验。计算值与实验值的比较表明：相对于小周期情况(T=1.6s),该耦合计算模型在周期较大(T>≥2.0s)的情况下具有满意的精度。在短周期情况下(T=1.6s)波浪非线性特征不明显,但对较大周期(T=2.0s)非线性成分开始占有较大比例,特别是波高较大时(H=8cm)波面中二次谐波就有较大的值,对于长周期波(T=-3.0s),在与同样波高但较小的周期(T=2.0s)相比,波面中二次谐波幅值较大,并且同样存在着较大的三次到五次谐波。与波面升高相比,压力的非线性特征不很明显。最后,将三维耦合计算模型应用于计算边界更为复杂的船体周围的波浪场,验证了该耦合计算模型的适用性较广。更多还原

【Abstract】 The time-domain coupled model calculating nonlinear waves acting on marine structures is an important topic in ocean engineering. Using the coupled model to solve the wave propagation and the wave action on the offshore structures can avoid the limitation that scope of application is narrow, which is caused by simply using the potential flow model, viscous flow model or the Boussinesq equation model, etc. This paper study making the time-domain coupled model calculate the wave field acting on the marine structures that have more complex boundary. The whole computation domain is divided into inner domain and outer domain. The inner domain surrounding the cylinder is governed by the Laplace equation, which is solved by the finite element method. The other area is the outer domain and is governed by Boussinesq equations, which is solved by the finite difference method. Matching conditions on the interface boundaries are applied to couple the inner and outer domains.Firstly, introduce mesh generation technology of the finite element analysis software-ANSYS and apply it to grid division of inner domain of the cylinder model and ship model.Secondly, the nonlinear time-domain coupled numerical model is adopted to calculate the nonlinear wave pressure acting on a circular cylinder and wave surface elevation. Calculated values compared with the experiment values show that:compared to the situation of the short period(T=1.6s),the coupled computational model has satisfactory accuracy at the major period(T≥2.0s). In the case of short period (T=1.6s) the non-linear characteristics of wave aren’t obvious, but at the major period (T=2.0s) they have a higher proportion. At the situation of large height(H=8cm),the second harmonic wave have larger values.Compared with the same wave height in smaller period(T=2.0s),the second harmonic of wave-front has larger amplitude and also has three to five times larger harmonic at the long period waves (T=3.0s). The non-linear characteristics of wave pressure isn’t very clear compared to the case of wave elevation.Finally, apply the three-dimensional calculation model to calculate wave acting on the hull. Verify the applicability of the coupled model.更多还原