Mechanics of Sediment Transport in Complex Flows

复杂水流中泥沙输送的力学

• 批准号: 9634261
• 负责人: Stephen McLean
• 金额: --
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-15 至 2001-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9634261&HistoricalAwards=false
• 关键词: Mechanics; Sediment; Transport; Complex; Flows

ABSTRACT Proposal Number: CTS 9634261 Principal Investigator: McLean This is a grant to support the investigation of the mechanics of sediment entrainment and transport in situations where near-bed mean flow and turbulence structure is significantly different than that of steady, uniform flows. This will be done within the context of an overall goal of developing the capability to predict the flow and sediment dynamics over an erodible bed and the resulting topographic response. Existing relations between flow characteristics and sediment transport developed in steady, uniform flows yield inaccurate results for more complex flows. This error arises through the alteration of the distributions of lift and drag forces on sediment grains making up the bed as a result of the effects of spatial and temporal accelerations on the turbulence field. These effects are a critical part of the mutual interactions between flow structure, sediment transport, and bed morphology that give rise to a wide spectrum of erodible bed phenomena, such as the formation and stability of ripples and dunes. The principle aims of this research are threefold: a) to extending the knowledge gleaned from two-dimensional bedforms to three-dimensional features b) to determine the response of a sediment particle to complex flow and c) to extend this information to suspended particles through the use of a multi-frequency acoustic backscatter system as well as with an imaging fiber optic system for observing very near-bed processes. Measurements will be combined with an advection/diffusion model for suspended sediment to investigate the nature of the relationship between local entrainment at the bed and the near-bed flow field and how this affects the evolution of the bedforms.

摘要 提案编号：CTS 9634261 首席研究员：McLean 这是一笔拨款，用于支持在近床平均流和湍流结构与稳定均匀流显着不同的情况下研究沉积物夹带和输送的力学。这将在开发预测侵蚀床上的流量和沉积物动力学以及由此产生的地形响应的能力的总体目标的背景下完成。在稳定、均匀的流动中发展起来的流动特征和沉积物输送之间的现有关系对于更复杂的流动产生不准确的结果。该误差是由于空间和时间加速度对湍流场的影响而改变构成床层的沉积物颗粒上的升力和阻力分布而产生的。这些效应是流动结构、沉积物迁移和河床形态之间相互作用的关键部分，导致了广泛的侵蚀河床现象，例如波纹和沙丘的形成和稳定性。这项研究的主要目标有三个：a）将从二维床形收集到的知识扩展到三维特征；b）确定沉积物颗粒对复杂流动的响应；c）通过使用多频声学反向散射系统以及用于观察非常近床层过程的成像光纤系统，将这些信息扩展到悬浮颗粒。测量结果将与悬浮沉积物的平流/扩散模型相结合，以研究河床局部夹带与近河床流场之间关系的性质，以及这如何影响河床形态的演变。