The interaction between breaking internal waves and gravity currents on inclined slopes

本研究旨在了解和量化倾斜斜坡上的重力流与在两层分层流体中传播的一系列传入内波之间的相互作用。这一目标将主要通过实验室实验来实现，结果将与数值模拟和实地测量相比较。重力流和破碎的内波在近海岸的海洋中都很常见。重力流携带的流体和物质的混合是理解陆地和海洋如何耦合的关键过程。目前迫切需要更详细地了解这种混合过程，因为全球采用海水淡化的压力越来越大，以应对未来的淡水短缺。这些沿海的海水淡化厂将高浓度的盐水排放到海洋中，假定它与接收的海水混合在一起。然而，目前这种混合过程的模型通常忽略了沿海海洋的流动，导致对混合的估计非常不正确，从而导致这些流出物对环境的影响。该项目将提供必要的基础科学，以缩小这一知识差距并改进这些模型。该项目的结果将对参与设计和允许沿海设施（如海水淡化厂）向近海岸海洋排放污水的工程师和政策制定者产生重大影响。本研究结果将通过与斯坦福大学从事翻译活动的同事交流，传达给相关利益相关者。该项目将支持一名年轻的研究人员完成博士学业，并向硕士生介绍环境和地球物理流动的研究，从而为教育做出贡献。最后，外展活动将通过鲍勃和诺玛街环境流体力学实验室运行的程序进行。在实验中，恒定流量的重力电流将沿着斜坡流入两层分层的环境流体。同时，在斜斜上传播的多个渐进式内波将与重力流相互作用，改变重力流与周围流体混合的方式。通过染料成像和定量平面激光诱导荧光相结合的方法，将测量重力流流体的命运变化及其与周围流体混合的方式。实验将进行广泛的相关重力流理查德森数和内波弗劳德数。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research seeks to understand and quantify the interaction between a gravity current on an inclined slope and a series of incoming internal waves propagating in a two-layer stratified fluid. The objective will be pursued primarily using laboratory experiments, and the results will be contextualized by comparison with numerical simulations and field measurements. Both gravity currents and breaking internal waves are common in the near-coastal ocean. The mixing of the fluid and material carried by the gravity current is a key process in understanding how the land and sea are coupled. There is also a pressing current need to understand this mixing process in more detail due to increasing pressure globally to adopt seawater desalination as a hedge against future freshwater scarcity. These coastal desalination plants discharge highly dense brine effluent into the ocean, where it is assumed to mix with the receiving ocean waters. However, current models of this mixing process typically neglect flow in the coastal ocean, leading to wildly incorrect estimates of the mixing and thus the environmental impact of these effluents. This project will provide the basic science needed to close this knowledge gap and improve these models. The results of this project will be of key interest to engineers and policymakers involved in designing and permitting coastal facilities such as desalination plants the discharge effluents into the near-coastal ocean. The results of this research will be communicated to relevant stakeholders by interacting with colleagues engaged in translational activities at Stanford. The project will contribute to education by supporting a young researcher through the end of his Ph.D. studies and introducing Masters students to research in environmental and geophysical flows. Finally, outreach activities will be pursued via programs run through the Bob and Norma Street Environmental Fluid Mechanics Laboratory.In the experiments, a constant-flux gravity current will flow down a slope into a two-layer stratified ambient fluid. At the same time, multiple progressive internal waves propagating on the pycnocline will interact with the gravity current, changing the way it mixes into the ambient fluid. The changes to the fate of the gravity-current fluid and the way it mixes into the ambient fluid will be measured with a combination of dye imaging and quantitative planar laser-induced fluorescence. Experiments will be performed for a wide range of relevant gravity-current Richardson numbers and internal wave Froude numbers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.