Modelling Extreme Free-Surface Flows: applications to breaking waves, wave-structure and wave-vessel interactions

拟议的研究涉及极端自由面流动的描述，在深水近海和浅水沿海位置都有应用。这项工作将涉及开发一种新的数值模式，适用于描述大型表面水波及其与固定结构物和浮动船只的相互作用。连接这些流动的关键特征将是波浪破碎的发生；包括水面的破裂、空气的夹带和高度湍流区的快速发展。从实用的角度来看，这种流动是极其重要的，因为它们与最高(限制)的水面高度、最大的水颗粒速度和最大施加的流体负荷有关。为了模拟这类流动，并提供更好的物理理解，新的数值模型将结合两种截然不同的建模方法的优点：在波浪破碎开始之前应用边界元方法，以及应用于破碎和破碎后的流体流动的光滑粒子流体动力学。通过结合这些程序，建议的方法将寻求创建一个健壮和准确的模型，能够描述广泛的自由表面流动；特别注意那些对设计至关重要且无法用现有求解程序描述的波-结构和波-船相互作用的方面。模型预测将与新的实验室观测结果进行验证。这将涉及使用缩尺物理模型试验，并将考虑广泛的实际重要的流体流动，包括：(I)破碎波，包括大范围的倾覆和溢流波；(Ii)波浪-结构相互作用中的高度非线性效应，包括高频波散射，垂直射流，其中流体向上投射到极高的海拔造成甲板上的波浪载荷，以及波浪对垂直柱和甲板结构的冲击；(Iii)波浪与船只的相互作用，特别是绿水淹没和大冲击力的发生。为了解决这些问题，实验和数值研究将寻求提供新的物理理解，以了解这些事件发生的时间和原因，评估它们的实际影响，并确定如何在工程实践中最好地模拟它们。拟议的工作与流体力学中的一系列问题有关，特别是应用于海洋结构物的有效设计和安全操作。提案中纳入了来自三个主要行业从业者的直接支持。该项目还将与可再生能源行业相关。由于有兴趣在大风和海浪活动较大的地区建立海上风电场，这类结构非常容易受到大规模海浪破碎和相关冲击力的影响。航运业也将从这个项目中受益：新的模式提供信息，以改进船舶的设计和/或安全操作，既提高生存能力，又限制大规模环境影响和破坏的可能性。最后，这项工作还具有真正的多学科贡献，超越了沿海/近海/脐带建筑的边界，因为水面的破裂(特别是空气的夹带)总体上对海-气相互作用，特别是质量交换(二氧化碳吸收)具有影响。这些问题对海洋学家研究海洋表面的转移过程至关重要，是气候变化模型的一个关键因素。

The proposed research concerns the description of extreme free-surface flows with applications in both deep water offshore and the shallow water coastal locations. The work will involve the development of a new numerical model appropriate to the description of large surface water waves and their interaction with both fixed structures and floating vessels. The key feature linking these flows will be the occurrence of wave breaking; involving the break-up of the water surface, the entrainment of air and the rapid development of areas of highly turbulent flow. From a practical perspective such flows are extremely important because they are associated with the highest (limiting) water surface elevations, the largest water particle velocities and the maximum applied fluid loads. As a result, they are directly relevant to the design of all manner of marine structures and vessels.In order to simulate such flows, and in so doing provide improved physical understanding, the new numerical model will combine the advantages of two very different modelling procedures: a Boundary Element Method applied before the onset of wave breaking and Smooth Particle Hydrodynamics applied to the breaking and post-breaking fluid flow. By combining these procedures the proposed method will seek to create a robust and accurate model capable of describing a wide range of free-surface flows; particular attention being paid to those aspects of wave-structure and wave-vessel interactions that are critical for design and cannot be described by existing solution procedures.The model predictions will be validated against new laboratory observations. This will involve the use of scaled physical model tests and will consider a wide range of practically important fluid flows including:(i) Breaking waves, including both large-scale over-turning and spilling waves;(ii) Highly nonlinear effects in wave-structure interaction, including high-frequency wave scattering, vertical jetting where fluid is projected upwards to very high elevations creating wave-in-deck loads, and wave slamming on both vertical columns and the deck structure;(iii) Wave-vessel interactions, particularly the occurrence of green water inundation and large impact forces.In tackling these problems, the combined experimental and numerical studies will seek to provide new physical understanding of when and why these events occur, to assess their practical implications and to identify how they can best be modelled in engineering practice.The proposed work is relevant to a wide range of problems in fluid mechanics, with particular application to the effective design and safe operation of marine structures. Direct support from three key industrial practitioners is incorporated within the proposal. The project will also be relevant to the renewable energy industry. With interest in locating offshore wind farms in areas of high wind and therefore large wave activity, such structures are very susceptible to large-scale wave breaking and the associated impact forces. The shipping industry will also benefit from this project: the new model providing information to improve the design and/or safe operation of vessels to both increase survivability and, in the case of oil tankers, limit the potential for large-scale environmental impact and damage. Finally, the work also has a truly multi-disciplinary contribution, beyond the coastal/offshore/navel architecture boundaries, in the sense that the break-up of the water surface (specifically the entrainment of air) has implications for air-sea interactions in general, and mass exchange (CO2 absorption) in particular. Such issues are of fundamental importance to oceanographers studying the transfer processes at the ocean surface and contribute a key element to climate change modelling.