海洋结构物大幅度运动剧烈流场数值模拟方法研究

The aim of this project is to develop an overset grid method suitable for both structured meshes and unstructured meshes based on our existing overset multi-block method coupled with advanced interpolating techniques and mesh element searching techniques in order to break the bottleneck of the traditional meshes in handling the 6 degree-of-freedom(DOF) and large amplitude motion of ocean structures in violent flows. Several modules, including implementation module of the newly developed overset grid method, 6DOF motion module of body, data interface module for the match of overset grid method with OpenFOAM, as well as the module of numerical wave generation and elimination of wave, will be developed under the platform of an open souce package OpenFOAM. A specialized solver, called naoeFlows which is used for the numerical simulations of violent flows with 6DOF large amplitude motion of ocean structures in waves, will be developed by the integration of all the abovementioned newly developed modules in the frame of OpenFOAM. The research results of this project can overcome the difficulties of solving the problem of the large amplitude motion of body in violent flows, and effectively fullfil the numerical simulation of complex violent flows with 6DOF large amplitude motion of ocean structures, as well as the complex flows with multi-bodies motion, including the ship rolling motion with big angle greater than 20 degrees, ship capsize, green water flows, ship hull-rudder-propeller interaction, interaction of multi-ship motions, floating platform and FLNG in heavy sea, etc.

本项目针对传统网格在处理海洋结构物六自由度大幅度运动问题的瓶颈，将在申请人已开发的适合结构化网格的嵌套网格Overset multi-block方法的基础上，结合先进的插值技术和单元搜索技术，发展适用于结构化网格和非结构化网格的嵌套网格方法。在开源代码OpenFOAM平台上，开发嵌套网格实现模块，物体六自由度运动(6FOF)模块，嵌套网格与OpenFOAM结合的数据接口模块，数值造波和消波功能模块，并共同集成到OpenFOAM中，形成一个专门面向船舶与海洋工程水动力学问题的求解器naoeFlows，数值模拟海洋结构物六自由度大幅度运动引起的复杂剧烈流动问题。本项目的研究成果，可以有效实现海洋结构物在波浪中大幅度运动以及多物体运动相互作用问题的数值模拟，包括船舶大于20 的横摇和倾覆问题；以及甲板上浪，船桨舵相互作用，多船运动相互作用，海洋平台和FLNG在大波浪中运动和动力响应等问题。

本项目针对传统网格在处理海洋结构物六自由度大幅度运动问题的瓶颈，利用先进插值和单元搜索技术，改进原有嵌套网格Overset multi-block方法，研究开发了适用于结构化网格和非结构化网格的嵌套网格方法。在开源代码 OpenFOAM 平台上，开发了嵌套网格实现模块、物体六自由度运动(6FOF)模块、嵌套网格与 OpenFOAM 结合的数据接口模块、数值造波和消波功能模块，然后共同集成到 OpenFOAM 中，形成了一个专门面向船舶与海洋工程水动力学问题的求解器naoe-FOAM-SJTU，并成功应用于海洋结构物六自由度大幅度运动引起的复杂剧烈流动问题的数值模拟。本项目所研发的嵌套网格方法和新构建的流场求解器naoe-FOAM-SJTU，很好实现了船舶与海洋结构物在高海况下六自由度大幅运动问题的数值模拟，包括船舶大于20°的横摇问题和倾覆问题，甲板上浪，船桨舵相互作用，多船运动相互作用，海洋平台和FLNG在大波浪中运动和动力响应等问题，不仅实现了三维数值波浪水池、六自由度运动和多级物体运动求解以及系泊系统等功能模块，也在船舶静水阻力、耐波性、船舶自航推进和自航操纵等领域得到验证和应用。通过本项目计算研究和比较验证，表明本项目研究获得的重叠网格技术和开发的CFD求解器naoe-FOAM-SJTU，在数值模拟复杂船舶流动问题方面有很好的适用性和可靠性，为高海况下的船舶与海洋工程复杂流动与运动问题提供了一个新的有效求解工具和手段。