High-fidelity Simulation of Air Entrainment in Breaking Wave Impacts

全球气候变化增加了发生更多极端天气事件的可能性，这些事件的强度更高，持续时间更长。强风和高海平面产生了更多的巨浪，使它们比以前更接近英国的海岸。海岸线、海上平台、可再生能源转化器和海洋船舶遭受风暴袭击，其完整性受到强烈海浪冲击的威胁。这种极端事件还对飞机在海上的紧急降落，特别是抛落直升机，以及在公海状态下从较大船只上下水和回收救生艇的行动提出了挑战。为了减少这种自然灾害对英国公共安全和经济活动带来的不确定性和风险，研究、工业和政府机构至关重要，通过开发和使用结合数学和物理科学以及最新软件工程技术的高保真新一代自由表面模拟工具，准确预测极端海浪载荷和由此造成的损害，来改进海岸和近海结构物的设计。该项目的总体目标是开发这样一种强大的数值工具，使学者和工业用户能够获得新的科学见解，并更好地了解波浪破碎过程中的空气卷吸过程。这将有助于确定波浪破碎前/中/后的临界掺气水平和分布，并通过CFD模拟预测其对海岸和近海结构物的冲击荷载特性。这将通过重新设计和扩展现有的新型可压缩多相水力程序的能力来实现，该程序结合了先进的双流体混合湍流模拟方法、流体表面张力和由最先进的高性能计算设施部署的自适应高阶数值离散格式。该项目产生的工具和数据的可用性和使用将坚定地支持学者和工程师修改/改进关键国防系统的设计，以应对日益严重的环境挑战、保护宝贵的个人和公共资产、保护当地居民和通勤者，并确保运输线的完整性。这将有助于保持英国的经济-环境-社会竞争力和长期可持续发展。

Global climate change is increasing the odds of more extreme weather events taking place which will have higher intensity and longer duration. Strong winds and high sea levels generate more large waves and drive them much closer to the UK's shore than before. The coastline, offshore platforms, renewable energy converters and marine vessels are battered by storms, and their integrity is placed under the threat of violent wave impact. Such extreme events also challenge the emergency landing of aircraft in the sea particularly ditching helicopters as well as the launch and recovery operations of lifeboats from larger vessels under high sea states. To mitigate the uncertainties and risks posed by such natural hazards on the public safety and the economic activity of the UK, it is vital for research, industry and governmental bodies to improve the design of coastal and offshore structures through the accurate prediction of the extreme wave loadings and the resultant damage by the development and use of high-fidelity new generation free surface modelling tools, which combine mathematical and physical science as well as the latest software engineering technology.The overall aim of this project is to develop such a powerful numerical tool to enable academics and industrial users to gain new scientific insights and better understanding of the air entrainment process in wave breaking. This will help determine the critical aeration level and distribution before/within/after wave breaking, and predict the characteristics of the resultant impact loadings on coastal and offshore structures through CFD simulation. This will be accomplished by re-engineering and extending the capabilities of an existing novel compressible multiphase hydro-code incorporating an advanced two-fluid hybrid turbulence modelling approach, fluid surface tension and adaptive high order numerical discretisation schemes deployed by state-of-the-art HPC facilities.The availability and use of the tools and data produced by the project will firmly support academics and engineers to modify/improve the designs of crucial defence systems in order to address increasing environmental challenges, protect valuable personal and public assets, safeguard local residents and commuters, and ensure the integrity of transport lines. This will help to maintain the economic-environmental-societal competitiveness and long-term sustainable development of the UK.