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

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.

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。

本项目围绕剧烈流动下船舶与海洋结构物的流固耦合问题，针对三维自由面变化剧烈，结构响应多模态和强非线性，数值仿真的计算量大，计算精度和稳定性要求高等需求，充分发挥粒子法-有限元混合方法及求解软件兼备粒子法和有限元法的优点，研究形成了适用于剧烈流动下的三维流固耦合粒子法-有限元高性能混合方法，突破了计算效率、精度和稳定性方面的瓶颈，解决了三维流固耦合数值方法难以校核验证的问题；开发形成了具有完全自主知识产权的流固耦合高性能仿真软件；通过设计流固耦合物理试验和标模问题，验证了本项目所研发的粒子法-有限元混合方法及软件在三维剧烈流动下的流固耦合仿真计算精度，很好解决了船舶与海洋工程中带剧烈变化自由面的三维流固耦合问题，真实地捕捉了船舶与海洋工程中的波浪翻卷、破碎、飞溅、融合等剧烈流动现象，以及多种砰击、波激振动、颤振等结构非线性响应现象，揭示了多种深远海复杂环境下柔性结构物的流固耦合复杂作用机理，对深远海新型海上结构物设计制造的性能评估提供了有力分析工具。发表论文113篇，其中SCI收录42篇，EI收录36篇，中文核心35篇，获6项软件著作权。培养毕业与本项目研究方向相关的4名博士生和6名硕士生，项目组成员有50多人次参加国内外学术会议交流，主办4次国际会议，2次国内会议，邀请了国内外5位知名专家做了学术报告和专题讲座。