【作者】 王化明；

【导师】 邹早建； 高高；

【作者基本信息】 武汉理工大学 ， 流体力学， 2005， 硕士

【摘要】 相对于理论和试验方法，用数值方法计算船舶水动力具有其独特的优点和发展潜力。上世纪60年代至今，随着计算机科学技术的发展，计算流体动力学(CFD)取得了重大的进展。CFD应用于船舶水动力学问题的数值求解，产生了船舶CFD方法。随着船舶CFD技术被越来越广泛地应用于实际工程问题，势流法求解船舶水动力学问题的快捷性和精确性越来越重要，应用高阶面元法求解船舶水动力问题成为当今的一个研究热点。近年来，出现了众多的高阶面元法，其中基于被国际标准化组织(ISO)规定为定义工业产品几何形状的唯一数学描述工具的非均匀有理B样条(NURBS)的高阶面元法因为可以和船舶计算机辅助设计(CAD)更好地结合，更方便快捷地进行船型设计和船舶水动力性能设计、优化，因而具有相当好的发展前景。 本文采用Rankine源作为Green函数，采用非均匀有理B样条(NURBS)来表达物面几何及源强分布密度，采用频域法对自由面边界条件进行线性化处理，开发了一种基于NURBS的Rankine高阶面元法，用于数值计算考虑自由面边界条件的有航速船舶微幅摇荡运动水动力系数，以模拟试验水池中的约束船模平面运动机构(PMM)试验。由于源强分布密度采用NURBS的高阶表示方法，克服了常数面元法源强分布密度不连续的缺陷，能够精确高效地计算求解辐射问题的频域法中出现的所谓的“m”项，从而有效地计算船舶摇荡运动水动力系数。 为了验证本文开发的高阶面元法的有效性，首先对无界流场中的球体及一般椭球体的附加质量进行了数值计算，并将计算结果和理论结果进行了比较。随后，以近水面椭球体和Wigley数学船型为例，对计及自由面兴波的有航速物体摇荡运动水动力进行了计算，给出了第2、6运动模式下的附加质量和阻尼系数。通过对算例数值结果的分析，得出了一些初步的结论。更多还原

【Abstract】 Compared with the theoretical and experimental methods, numerical method has some merits in predicting ship hydrodynamic performances. Since 1960’s, with the development of computer science and technology, many breakthroughs have been obtained on the Computational Fluid Dynamics (CFD). The application of CFD in resolving ship hydrodynamic problems results in a new branch in ship hydrodynamics — ship CFD. As ship CFD is more and more widely used in engineering problems, accurate and rapid solution of ship hydrodynamic problems by potential theory method becomes more and more important. One of the focuses of recent researches is to solve the ship hydrodynamic problems using higher-order panel method. In recent years, many higher-order panel methods have been proposed, and among them the higher-order panel method based on the Non-Uniform Rational B-Splines (NURBS) is most promising due to its merits that it can be combined with the Computer Aided Design (CAD) and conveniently used in ship design from the point of view of ship hydrodynamic performances.In this thesis, a higher-order panel method based on NURBS has been developed for computing the hydrodynamic coefficients of a ship undergoing a forward motion and an oscillating motion of small amplitude, with the free surface effects being taken into account. Rankine source is employed as the Green function, and NURBS is used to describe the body geometry and the distribution of the source strength. The free surface boundary conditions are linearized so that the boundary-value problem is formulated and solved in frequency domain. The proposed method can be used to simulate the flow of captive model tests by PMM to determine the hydrodynamic coefficients with high accuracy and efficiency.The proposed method is firstly applied to calculate the added mass of a sphere and spheroids moving in unbounded fluid. The numerical results are compared with the theoretical ones to check the validity of the proposed method. Then the method is used to solve the radiation problem with forward speed effects for a submerged spheroid and a Wigley mathematical model of surface ship. The numerical results ofhydrodynamic coefficients for 2nd and 6th mode of ship motion are presented and discussed. Some conclusions are drawn from the analysis of the computation practice and the numerical results.更多还原