How does aquatic vegetation modify the kinematic & geometric characteristics of coherent flow structures in open channels?

水生植物如何改变运动学

• 批准号: NE/G009333/1
• 负责人: Richard Hardy
• 金额: $ 4.76万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG009333%2F1
• 关键词: How; does; aquatic; vegetation; modify

Vegetation within river channels has a profound influence on the functioning and therefore management of fluvial systems. It can significantly effect: i) the flow resistance and thus influence water conveyance and therefore potentially increase flood risk; ii) erosion, deposition and sediment transport rates; and iii) the biological activity within the fluvial system. On a smaller spatial scale, vegetation also generates turbulence that drives both mixing and diffusion processes with strong velocity gradients generated around and above submerged macrophytes and canopies. Fluvial flow has traditionally been analysed and modelled on a time-averaged, continuum basis, but it is well known that large turbulent fluctuations exist in near-bed velocity. The aim of this research is to develop an enhanced quantitative understanding of the effect of aquatic vegetation on the generation, evolution and dissipation of Coherent Flow Structures in the fluvial system. This will be achieved by a series of state of the art laboratory flume experiments using novel automated turbulence mapping techniques in the UK's best-equipped environmental fluid dynamics laboratory. The techniques give a combined Eulerian and Lagrangian view of Coherent Flow Structures revealed by injecting tracers into the flow that allows us to monitor and thus understand both the kinematic (size, scaling, shape, vorticity and energy) and dynamic properties (origin, stability, growth, genesis into new forms and contribution to the time average flow) of these Coherent Flow Structures as they are produced and move over and through aquatic vegetation. The proposed methodology will allow us to both increase our phenomenological understanding of Coherent Flow Structures in fluvial systems and develop a framework for including aquatic vegetation into numerical model (a Computational Fluid Dynamics scheme) of river flow. This will provide a first order estimation of the increased drag from the presence of vegetation which will enable an improved parameterisation of the roughness coefficient in flood models.

河道内的植被对河流系统的功能和管理有着深远的影响。它可以显著影响：i）流动阻力，从而影响水的输送，从而潜在地增加洪水风险; ii）侵蚀、沉积和沉积物输运速率;以及iii）河流系统内的生物活动。在较小的空间尺度上，植被也会产生湍流，驱动混合和扩散过程，在水下植物和树冠周围和上方产生强烈的速度梯度。传统上对河流水流的分析和建模是基于时间平均的连续介质，但众所周知，近床流速存在较大的湍流波动。本研究的目的是开发一个增强的定量了解水生植被的生成，演变和消散的相干流结构在河流系统中的影响。这将通过一系列最先进的实验室水槽实验，使用新的自动湍流映射技术在英国最好的装备环境流体动力学实验室的状态来实现。该技术给出了通过将示踪剂注入流动中揭示的相干流结构的欧拉和拉格朗日相结合的观点，这使得我们能够监测并从而理解运动学和物理学。（尺寸、尺度、形状、涡度和能量）和动力学性质（起源、稳定性、增长、形成新的形式和对时间平均流量的贡献）这些相干流结构，因为他们的生产和移动，并通过水生植被。所提出的方法将使我们既增加我们的现象学理解的相干流结构的河流系统，并制定一个框架，包括水生植被的河流流量的数值模型（计算流体动力学方案）。这将提供一个一阶估计的阻力增加，从植被的存在，这将使一个改进的参数化的粗糙度系数在洪水模型。

项目成果

High-resolution numerical modelling of flow-vegetation interactions

水流与植被相互作用的高分辨率数值模拟

• DOI: 10.1080/00221686.2014.948502
• 发表时间: 2014
• 期刊: Journal of Hydraulic Research
• 影响因子: 2.3
• 作者: Marjoribanks T

The hydraulic description of vegetated river channels: the weaknesses of existing formulations and emerging alternatives

• DOI: 10.1002/wat2.1044
• 发表时间: 2014-11
• 期刊: Wiley Interdisciplinary Reviews: Water
• 作者: T. Marjoribanks;R. Hardy;S. Lane

On validating predictions of plant motion in coupled biomechanical-flow models

验证耦合生物力学流动模型中植物运动的预测

• DOI: 10.1080/00221686.2015.1110627
• 发表时间: 2015
• 期刊: Journal of Hydraulic Research
• 影响因子: 2.3
• 作者: Marjoribanks T

Modeling complex flow structures and drag around a submerged plant of varied posture

• DOI: 10.1002/2016wr020186
• 发表时间: 2017-04-01
• 期刊: WATER RESOURCES RESEARCH
• 影响因子: 5.4
• 作者: Boothroyd, Richard J.;Hardy, Richard J.;Marjoribanks, Timothy I.
• 通讯作者: Marjoribanks, Timothy I.

The importance of accurately representing submerged vegetation morphology in the numerical prediction of complex river flow

• DOI: 10.1002/esp.3871
• 发表时间: 2016-03-30
• 期刊: EARTH SURFACE PROCESSES AND LANDFORMS
• 影响因子: 3.3
• 作者: Boothroyd, Richard J.;Hardy, Richard J.;Marjoribanks, Timothy I.
• 通讯作者: Marjoribanks, Timothy I.