适用剧烈流动下流固耦合问题的三维无网格粒子法与有限元混合方法

深远海环境下，船海工程的流固耦合问题具有自由面变化剧烈，结构变形三维效应强，局部振动频率高等特点。粒子类方法采用无固定拓扑关系的粒子点对计算空间进行离散，非常容易处理剧烈流动及结构变形问题，再加上粒子法核函数和有限单元法形函数具有天然的插值功能，可实现粒子法和有限元法的无缝匹配，故而采用粒子法和有限元的混合方法求解剧烈流动下的流固耦合问题具有独特优势。然而，针对剧烈流动引起的三维流固耦合问题，由于流体-固体匹配复杂，计算量大等困难，目前三维无网格粒子法与有限元混合方法的研究还不多。针对这个问题，本项目着重研究三维无网格粒子法-有限元混合方法，发展和利用GPU加速技术、多分辨率粒子分布技术和改进粒子离散模型，研发一套效率高和稳定性强的三维无网格粒子法-有限元计算程序，通过标模数据进行考核验证。研究成果可为深远海复杂环境下剧烈流动引起的流固耦合问题，提供有效的计算分析手段。

In severe ocean environments, the interaction between waves and the ship and offshore structures can be charactered as the violent evolutions of water surface, strongly three-dimensional effects of the structural deformations, high frequencies of the structural vibrations, etc. In describing the above characteristics, the particle methods show significant advantages since they discrete the computational space by the particles which are of unfixed topology between each other. Besides, the kernel functions of particle methods and the shape functions of the finite element method have the natural capability of data interpolation, which can be utilized for the cooperation between the two kinds of methods. Therefore, the particle - finite element hybrid method is dominant in solving the fluid structure interaction problems induced by violent flows. However, the relevant methods for the complicated 3D FSI problems is still insufficiency. The analysis tools of the nonlinear problems are also absent. To identify and investigate the critical FSI problems for ship and offshore structures, a 3D particle - finite element hybrid method is proposed in this project. The calculation performance of the hybrid method is improved from the aspects of efficiency, accuracy and stability, by employing the accelerated calculation technique and several modifications of mathematical models. In addition, the numerical benchmark cases are carried out to validate the accuracy of the proposed hybrid method for 3D FSI problems. The outcomes of this project are expected to offer scientific foundation and innovative analytical tools for the safety evaluation of the new designed and manufactured ship and offshore structures.