Vortex Systems in Shallow Water

浅水中的涡流系统

• 批准号: 9803734
• 负责人: Donald Rockwell
• 金额: $ 30万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9803734&HistoricalAwards=false
• 关键词: Vortex; Systems; Shallow; Water

Abstract Proposal Number: CTS-9803734 Principal Investigator: Rockwell The objectives of this investigation are to gain a basic understanding of the vortex development, interaction and decay in shallow water. Large-scale vortical motions in jets, wakes, and mixing-layers occur in shallow free-surface configurations are diverse such as an open channel with flood plains, an embankment along a river, a sudden expansion of a surface waterway, a reservoir or lake inlet, the confluence of channels or rivers, a coastal shelf zone, a bridge abutment, and an isolated blunt obstacle such as a pier, island or cluster of vegetation. The development of these vortices has important consequences for thermal mixing, mixing of scalars, resonant oscillations of channels and harbors (seiches), overall performance characteristics of channel and river confluences, and the averaged discharge capacity of complex channels for flood routing. Furthermore, in all of these configurations, the underlying bed may be subject to scour or erosion due to the unsteady and time-averaged bed loading induced by vortex motions. In contrast to vortex development and interaction in shear layers of large spanwise extent, very little is known of the vortex structure in shallow water bounded by a free-surface and a bed (solid) surface. The first global, instantaneous representations of the two- and three-dimensional vortex structure will be attainable using recently developed techniques of high-image-density particle image velocimetry (HID-PIV). This approach will yield the space-time patterns of instantaneous vorticity and related topological features central to understanding the vortex development, vortex-vortex interactions, and vortex decay. Such an approach provides a physical basis for determining the classical turbulence statistics and mixing efficiency. A better understanding of the connection between vortex structure and bed scour and erosion can lead to new types of control techniques. In the near-field o f vortex development, small perturbations will substantially alter the initially-formed vortices and the rapidly developing three-dimensional vortex structure. In the far field, where the large-scale, quasi-two-dimensional vortical structures are expected to develop, control will take the form of spatial and temporal alterations of the bed friction and normal velocity at the bed; and localized generation of secondary concentrations of vorticity that may constructively or destructively interfere with the incident vortical structures. 2 1

摘要 提案编号：CTS-9803734 主要研究者：Rockwell 本研究的目的是获得一个基本的了解涡的发展，相互作用和衰减在浅水中。 在射流、尾流和混合层中发生的大尺度涡动在浅自由表面结构中是多种多样的，例如具有洪泛平原的明渠、沿沿着河流的堤岸、水面航道的突然扩张、水库或湖泊入口、河道或河流的汇合处、沿海陆架区、桥台和孤立的钝障碍物，例如码头、岛屿或植被丛。 这些涡的发展有重要的后果，热混合，标量混合，共振振荡的渠道和港口（假潮），渠道和河流汇流的整体性能特征，以及复杂的渠道洪水演算的平均流量。 此外，在所有这些配置中，由于漩涡运动引起的不稳定和时间平均河床负荷，下垫面可能会受到冲刷或侵蚀。 与大展向范围剪切层中的涡的发展和相互作用相反，由自由表面和床（固体）表面限定的浅水中的涡结构知之甚少。 第一个全球性的，瞬时表示的二维和三维涡结构将达到使用最近开发的高图像密度粒子图像测速技术（HID-PIV）。 这种方法将产生瞬时涡度的时空模式和相关的拓扑特征，这些特征对于理解涡的发展、涡-涡相互作用和涡的衰减至关重要。 这种方法为确定经典湍流统计和混合效率提供了物理基础。 更好地理解旋涡结构和河床冲刷和侵蚀之间的联系，可以导致新类型的控制技术。 在旋涡发展的近场，微小的扰动将显著地改变初始形成的旋涡和快速发展的三维旋涡结构。 在远场，大规模的准二维涡结构预计将发展，控制将采取的形式的空间和时间的变化的床摩擦和正常的速度在床上;和本地化生成的二次浓度的涡，可能建设性或破坏性地干扰入射涡结构。 2 1