Unsteady Wave-Driven Circulation Cells Relevant to Rip Tides and Coastal Engineering

建议编号：CTS-0423877 PRINCIPAL调查员：Andrew B.KENNEDYINSTUTION：FLORIDAUNSTEADY大学与RIP潮汐和海岸工程有关的波浪驱动环流单元这笔赠款是为了研究无旋转和旋转波浪驱动的近岸流动中的波浪强迫和波动。该方法主要是理论和数值方法，但将利用现有的实验室和现场结果。现场和实验室观测记录了波浪驱动的近岸流动中的显著不稳定，其时间尺度远远大于典型的波浪周期，例如发生在激流中的波浪周期。众所周知，这些波动是由入射波强迫的不稳定性和平均流的自由不稳定性共同驱动的，但自由运动和强迫运动的相对重要性仍不清楚。甚至强迫旋转涨落与非旋转涨落的相对重要性也是完全未知的。这项研究的三项主要任务是：波浪强迫无旋和旋转涨落的分析研究；近岸自由和强迫水动力不稳定性的数值研究；以及环流稳定性的分析研究。技术方案的广泛影响包括对导致激流的近岸现象的理解，激流每年都会导致人死亡。除了激流造成的溺水，在各种情况下，了解海滩/海岸附近的水流情况也很重要，即海滩侵蚀(海岸工程的一个大的子领域)、幼虫生物的运输(对休闲和商业捕鱼有许多影响)以及珊瑚礁上的波浪环流。严格关注海滩，存在粪便指示细菌等污染物的运输问题，在美国，这些污染物可能导致海滩关闭，每年造成数亿美元或更多的损失。该提案的更广泛的社会影响包括向社区和教育部门广泛传播成果，其中包括对研究生的培训和将研究成果纳入课程。这笔赠款由海军研究办公室、沿海地球科学计划、代码321CG共同资助。

PROPOSAL NO.: CTS-0423877PRINCIPAL INVESTIGATOR: ANDREW B. KENNEDYINSTITUTION: UNIVERSITY OF FLORIDAUNSTEADY WAVE-DRIVEN CIRCULATION CELLS RELEVANT TO RIP TIDES AND COASTAL ENGINEERING This grant is to study wave forcing and fluctuations in irrotational and rotational wave-driven near-shore flows. The approach is primarily theoretical and numerical, but will make use of existing laboratory and field results. Field and laboratory observations have recorded significant unsteadiness in wave-driven near-shore flows with time scales much larger than a typical wave period, such a those occurring with rip tides. These fluctuations are known to be driven by some combination of unsteadiness in incident wave forcing and free instabilities of the mean flow but the relative importance of free and forced motions remains unknown. Even the relative importance of forced rotational versus irrotational fluctuations is wholly unknown. Three major tasks are stated for the study: Analytical study of wave-forced forced irrotational and rotational fluctuations; Numerical study of free and forced hydrodynamic unsteadiness in the near-shore; and Analytical study of circulation cell stability.Broader impacts of the technical proposal include understanding of near shore phenomena that lead to rip currents, which kill people every year. Besides drowning due to rip currents, understanding how flows near beaches/the shore work is important in a variety of contexts, namely beach erosion (a large sub-field of coastal engineering), transport of larval organisms (many implications for recreational and commercial fishing), and wave-driven circulation over coral reefs. Strictly focusing on beaches, there is the issue of transport of contaminants like fecal indicator bacteria that can lead to beach closures costing hundreds of millions of dollars or more every year in the US. The societal broader impacts of the proposal include wide dissemination of the results to the community and educational components, which include training of graduate students and integration of the research results into courses. This grant co-funded by the Office of Naval Research, Coastal Geosciences Program, Code 321CG.