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

提案编号： CTS-0423877主要制造商：ANDREW B。肯尼迪学院： 佛罗里达大学非稳定波浪驱动的波浪单元与裂潮和海岸工程有关。该基金将用于研究无旋和有旋波浪驱动的近岸流中的波浪强迫和波动。 该方法主要是理论和数值，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显着的不稳定性，在波浪驱动的近岸流的时间尺度远大于一个典型的波浪周期，如那些发生的撕裂潮。已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的某种组合驱动的，但自由和强迫运动的相对重要性仍然未知。甚至受迫转动涨落与无旋涨落的相对重要性也是完全未知的。 该研究提出了三项主要任务：波浪强迫的强迫无旋和旋转波动的分析研究;近岸自由和强迫水动力不稳定性的数值研究;以及环流单元稳定性的分析研究。 除了由于离岸流造成的溺水，了解海滩/海岸附近的水流如何工作在各种情况下都很重要，即海滩侵蚀（海岸工程的一个大的子领域），幼虫生物的运输（对娱乐和商业捕鱼的许多影响），以及珊瑚礁上波浪驱动的环流。 严格来说，海滩存在粪便指示细菌等污染物的传播问题，这可能导致美国每年关闭海滩，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研究成果，其中包括培训研究生和将研究成果纳入课程。这项赠款由海军研究办公室，沿海地球科学计划，代码321 CG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.