Flow Past Obstacles in Shallow Water: Wake Structure and Free-Surface Deformation

摘要CTS-0228110 DONALD O.本文研究的总体目标是对浅水中流过水平障碍物的尾流不稳定性、它们与自由表面变形的耦合以及这些特征对床面负荷的影响有一个基本的了解。 穿过洪水泛滥的河流和沿着海岸线的石油、天然气和水管道，严重洪水条件下淹没的桥面，河流中的沙丘，尾水中的低水头水力闸门，高速水力泄流时的消能工，以及沿沿着水力坡度控制结构的水流，都是产生漩涡结构的配置。 这些涡流通常与浅水层的自由表面的变形有关，在存在相邻床（底壁）的情况下。 耦合的无涡表面不稳定性的后果包括障碍物的定常和非定常负荷、河床冲刷/泥沙输运的负荷、河流或河道的局部共振振荡、由于障碍物引起的局部破坏而引起的污染物混合，河流的改变/该程序将通过产生涡的发生和演变的定量表示来提高浅水涡系的知识。结构和自由表面变形，这两者都发生在相邻床的存在下。 这些贡献将包括负载特性的障碍物和床，和他们的控制技术。 预计这一见解可以为理论模型和数值技术提供指导，此外，还可以加强工程实践中的设计指南框架。

ABSTRACTCTS-0228110DONALD O. ROCKWELLLEHIGH UNIVERSITY FLOW PAST OBSTACLES IN SHALLOW WATER:WAKE STRUCTURE AND FREE-SURFACE DEFORMATIONThe overall aims of this investigation are to acquire a fundamental understanding of wake instabilities, their coupling with free-surface distortion, and the influence of these features on the bed loading for the case of flow past horizontal obstacles in shallow water. Petroleum, natural gas, and water pipelines across flooded rivers and along coastlines, submerged bridge decks during severe flood conditions, sand dunes in fluvial rivers, low head hydraulic gates in tailwater, energy dissipaters at high-speed hydraulic discharges, and flow along hydraulic grade control structures are among the configurations that generate vortical structures. These vortices typically are linked to distortion of the free-surface of the shallow water layer, in presence of an adjacent bed (bottom wall). Among the consequences of the coupled vortex-free surface instabilities are steady and unsteady loading of the obstacle, loading of the bed with scour/sediment transport, locally resonant oscillations of the river or channel, mixing of pollutants due to local disruptions induced by the obstacle, and alteration of the river/channel resistance.This program will advance knowledge of shallow water vortex systems by yielding quantitative representations of the onset and evolution of vortical structures and free-surface distortion, both of which occur in presence of an adjacent bed. These contributions will include loading characteristics of the obstacle and the bed, and techniques for their control. It is anticipated that this insight can provide guidance for both theoretical models and numerical techniques and, in addition, enhance the framework of design guidelines in engineering practice.