Three-Dimensional Hydrodynamic Modeling of Flow and Sediment Transport in Complex River Channels

复杂河道水流和泥沙输运的三维水动力模型

• 批准号: 0087842
• 负责人: Peter Kitanidis
• 金额: $ 30万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-01 至 2005-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0087842&HistoricalAwards=false
• 关键词: Three; Dimensional; Hydrodynamic; Modeling; Flow

0087842KitanidisIt is recognized that three-dimensional flow dynamics influence river channel morphology and the movement and distribution of sediment within the channel. In channels with compound cross-section, pool-riffle sequences, and developed meander systems, the influence of three-dimensional velocity fields on secondary flow circulation has a profound effect on both the river hydrodynamics and the movement of sediment. The goal of this project is to develop and validate a three-dimensional hydrodynamic and sediment transport model suitable for detailed field-scale studies to investigate the influence of complex three-dimensional flow structure during high flow events in: (a) pool-riffle sequences, (b) compound channels, and (c) meandering compound channels. This study will investigate the influence of these flow structures on secondary circulation, and the erosion, deposition, and transport of sediment. The project utilizes an existing semi-implicit numerical model for non-hydrostatic free-surface flows on unstructured grids. The model is based on the three-dimensional Navier-Stokes equations and utilizes a semi-implicit algorithm that is robust, stable, and very efficient. The model will be coupled with a mobile bed model for suspended and bedload sediment transport.A thorough understanding of the flow and sediment regime in complex channels is essential for the planning and development of successful stream restoration efforts. One of the primary causes of failure in stream restoration is the placement of structures or the construction of channel designs that are not suitable for prevailing hydrologic and sedimentologic conditions. Current models cannot accurately predict flow and sediment transport within these channel forms during high flows, which makes it difficult to evaluate potential stability. The contributions of this work include: advancing current understanding of stream stability, channel morphology, flood conveyance, sediment transport, and flow variability in complex river channels, demonstrating the influence of three-dimensional velocity fields on flow and sediment transport in complex channels; investigating the applicability of the velocity reversal hypothesis as a mechanism for understanding sediment transport in pool-riffle sequences during high flows; modeling the influence of secondary circulation in straight and sinuous compound channels to quantify the influence of floodplains on sediment movement and flood conveyance; and demonstrating the capacity of hydrodynamic modeling to improve the planning and design of river restoration projects.

[00:87842 . kitanidis]人们认识到，三维水流动力学影响河道形态以及河道内泥沙的运动和分布。在具有复合断面、池沟序列和曲流系统发育的河道中，三维速度场对二次流循环的影响对河流水动力和泥沙运动都有深远的影响。该项目的目标是开发和验证一个三维水动力和泥沙输运模型，该模型适用于详细的现场尺度研究，以调查复杂的三维流动结构在高流量事件中的影响：(a)池-沟序列，(b)复合通道，和(c)蜿蜒复合通道。本研究将探讨这些水流结构对二次循环、泥沙侵蚀、沉积和输运的影响。该项目利用现有的半隐式数值模型，用于非结构化网格上的非静力自由表面流动。该模型基于三维Navier-Stokes方程，采用了一种鲁棒、稳定、高效的半隐式算法。该模型将与悬沙和床沙输运的移动床模型相结合。全面了解复杂河道的水流和泥沙状况对于规划和发展成功的河流恢复工作至关重要。河道修复失败的主要原因之一是构筑物的放置或河道设计的建造不适合当时的水文和沉积条件。目前的模型不能准确地预测这些河道形态在高流量时的水流和泥沙输运，这使得评估潜在稳定性变得困难。本工作的贡献包括：推进了当前对复杂河道中河流稳定性、河道形态、洪水输送、输沙和流量变异性的认识，展示了三维速度场对复杂河道中水流和泥沙输送的影响；研究流速反转假说在高流速条件下作为理解池-沟层序沉积物输运机制的适用性；模拟直弯复合河道二次环流的影响，量化洪泛区对泥沙运动和洪水输送的影响；论证了水动力模拟对河流修复工程规划设计的指导作用。