新型SPH造波算法及其在波浪与浮式结构物耦合模拟中的应用研究

The coupling between floating structure and waves is a widespread problem in engineering fields, such as the hinge and anchor constrained structures. These problems contain the complex free surface deformation and coupling with multiple degrees of freedom, which have became the research hotspots and difficult issues in coastal engineering. The Smoothed Particle Hydrodynamics (SPH) is a suitable mesh-free method for these problems, but the secondary wave reflection near wave maker limits the long time SPH simulation. In this study, based on above issues, a new wave maker theory will be presented for SPH model to eliminate the secondary reflection in numerical flume. Firstly, based on the N-S equations, two depth-resolved source term internal wave maker theories will be presented for SPH method, and their accuracy and reliability in different wave parameters will be investigated; Secondly, the treatment of the DOF constraint (hinge point and anchor line) method in SPH is investigated, then the verifications will be conducted in comparisons with the theoretical and experimental results; Lastly, the complex floating structure response to waves will be simulated using the integrated model, and the verification experiment will also be conducted. The present study can extend the SPH application to the simulation of the floating structures and provide an effective tool for engineering design.

工程中广泛存在铰接、锚链约束的浮式结构物与波浪的耦合作用问题包含了复杂的自由面变形和多自由度的流固耦合，对这些问题的数值模拟研究一直是海洋工程中的热点和难点问题。光滑粒子水动力学（SPH）方法特别适合模拟这类问题，但数值水槽中造波板附近的波浪二次反射限制了耦合模拟的长时间进行。本研究着眼于这些不足，采用内造波技术在SPH数值波浪水槽中消除二次反射影响并将其应用到浮式结构物模拟中。首先，通过改进现有理论提出基于NS方程的水深解析的SPH内造波算法，解决长时间模拟的二次反射问题，验证其精度和可靠性；而后提出浮式结构物典型自由度约束机构的SPH数值处理方案。最后，对真实波浪条件下浮式结构物运动进行数值模拟和简单实验验证，将SPH的应用范围拓展到浮式结构物对波浪响应的问题的模拟中。

复杂的自由面流固耦合问题的数值模拟研究一直是海洋工程中的热点和难点问题，如波浪与结构物耦合的模拟以及复杂运动结构物的模拟等。光滑粒子水动力学（SPH）方法特别适合模拟这类问题，但数值水槽中造波板附近的波浪二次反射极大地限制了耦合模拟的长时间进行。本研究着眼于这些不足，提出了适合于SPH方法的内造波（源项造波）算法，并将其应用在长时间波浪模拟研究中。.研究结果主要集中在适合SPH的内造波算法和复杂自由度约束机构的模拟算法两方面。内造波算法包括从经典网格法改进的水深平均动量源项、空间平均的点质量源项，以及水深解析的NS方程动量源项算法。研究结果表明除水深解析的NS方程源项理论基础尚未完善外，水深平均动量源项具有良好的稳定性和普适性，而空间平均的点质量源项则具有更好的灵活性改进空间。自由度限制模块包括具有普遍意义的零维单点铰链和一维直线锚链的算法，其中单点铰链可采用惯性力矩替代法直接模拟，而一维锚链则可以采用线性弹簧算法近似模拟，二者均可得到令人满意的结果。通过上述两大部分主要研究成果，形成了一整套可以进行长时间波浪结构物耦合模拟的无网格SPH数值计算模型，可以模拟各种复杂的波浪与运动结构物（铰接、锚链）运动。