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

本研究旨在了解和量化的重力流之间的相互作用的倾斜的斜坡和一系列传入的内波传播的两层分层流体。将主要通过实验室实验来实现这一目标，并将通过与数值模拟和实地测量进行比较来确定结果的背景。重力流和破碎的内波在近岸海域都很常见。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种混合过程，因为全球采用海水淡化作为未来淡水短缺的对冲措施的压力越来越大。这些沿海海水淡化厂将高浓度的盐水废水排入海洋，在那里与接收海水的沃茨混合。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错误，从而导致这些流出物对环境的影响。该项目将提供缩小这一知识差距和改进这些模型所需的基础科学。该项目的结果将对参与设计和允许海水淡化厂等沿海设施向近海排放废水的工程师和政策制定者产生重大影响。这项研究的结果将通过与在斯坦福大学从事翻译活动的同事互动传达给相关利益相关者。该项目将通过支持一位年轻的研究人员完成博士学位来促进教育。研究和介绍硕士生在环境和地球物理流的研究。最后，将通过鲍勃和诺玛街环境流体力学实验室开展的方案开展外联活动，在实验中，恒定通量的重力流将沿着斜坡流入两层分层的环境流体。与此同时，在密度跃层上传播的多个前进内波将与重力流相互作用，改变它与周围流体混合的方式。重力流流体的命运的变化以及它与周围流体混合的方式将通过染料成像和定量平面激光诱导荧光的组合来测量。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.