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

这项研究试图了解和量化倾斜坡面上的重力流与在两层分层流体中传播的一系列入射内波之间的相互作用。将主要利用实验室实验来实现这一目标，并将通过与数值模拟和现场测量进行比较来结合结果。重力流和破裂的内波在近岸海洋中都很常见。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。目前还迫切需要更详细地了解这一混合过程，因为全球越来越大的压力要求采用海水淡化来对冲未来淡水短缺的风险。这些沿海的海水淡化厂将高密度的盐水废水排放到海洋中，在那里它们被认为与接收海水的水混合。然而，目前这种混合过程的模型通常忽略了沿海海洋中的流动，导致了对混合的极不正确的估计，从而导致了这些污水对环境的影响。该项目将提供弥合这一知识差距和改进这些模型所需的基础科学。参与设计和允许海水淡化厂等沿海设施的工程师和政策制定者将对这一项目的结果产生重大兴趣，并将污水排放到近海。这项研究的结果将通过与斯坦福大学从事翻译活动的同事互动的方式传达给相关利益攸关方。该项目将通过支持一名年轻的研究人员完成他的博士学习，并向硕士学生介绍环境和地球物理流动研究，从而为教育做出贡献。最后，将通过Bob和Norma Street环境流体力学实验室的项目进行推广活动。在实验中，恒定通量的重力流将从斜坡上流下，进入两层分层的环境流体。与此同时，在跃层上传播的多个递进内波将与重力流相互作用，改变其与周围流体混合的方式。重力流流体的命运和它混合到周围流体的方式的变化将通过结合染料成像和定量平面激光诱导荧光来测量。实验将针对各种相关的重力流理查森数和内波弗劳德数进行。这一奖项反映了NSF的法定使命，并已通过使用基金会的智力优势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.