TURBULENT FLOW AND TRANSPORT IN OPEN CHANNELS WITH NATURAL ROUGHNESSES: EXPERIMENTS AND NUMERICAL SIMULATIONS

自然粗糙度明渠中的湍流和传输：实验和数值模拟

• 批准号: 183977-2013
• 负责人: Balachandar, Ramaswami
• 金额: $ 1.89万
• 依托单位: University of Windsor
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=569678
• 关键词: TURBULENT; FLOW; TRANSPORT; OPEN; CHANNELS

The presence of submerged vegetation in conveyance channels leads to an increase in flow resistance and reduction of channel flow capacity. For this reason, vegetation has often been removed from channel beds. Biologists and ecologists have recognized that submerged vegetation can provide a wide range of important ecosystem services. Aquatic vegetation helps reduce turbidity, remove nutrients, produce oxygen and alter sediment transport. Studying the interaction of turbulence with aquatic vegetation and its role in cycling nutrients, controlling erosion, and protecting riverbanks can have enormous ecologic and economic benefits. The fluid flow-plant interaction can be quite complex. Aquatic plants and the shear-layers that they generate can occupy a significant fraction of the total flow domain. The submerged plants can be flexible, coupling the motion of the fluid and the canopy. Besides being buoyant, flexible canopies can exhibit a coherent waving in response to the flow. The morphology of the vegetation can also play an important role in the posture due to the stem stiffness, which can influence the drag. A combined effect of stem stiffness, blade shape, positioning and their interaction with the flow is still not well understood. A universal description of drag for flexible aquatic vegetation remains elusive. The present research program is a step towards better understanding of the interaction of clusters of submerged vegetation and turbulence in open channels. The major goals include: (1) To study the major features of flow, turbulence and transport associated with flexible and rigid vegetation via experiments and numerical simulations and (2) To quantify the drag in the case of flexible vegetation that appear vital for understanding the fluid-plant interaction. (3) The fluid dynamics of finite patches of flexible and rigid vegetation and (4) Investigation of turbulence and coherent structures in the wake of the patch. Besides training HQP and influencing policy makers, the proposed research will also have a positive influence on other Windsor research programs as the numerical and experimental tools assembled for this project can be successfully employed in other investigations.

输送渠道中水下植被的存在导致水流阻力增加和渠道流通能力降低。因此，河床上的植被经常被清除。生物学家和生态学家已经认识到水下植被可以提供广泛的重要生态系统服务。水生植被有助于降低浊度、去除营养物质、产生氧气并改变沉积物运输。研究湍流与水生植被的相互作用及其在养分循环、控制侵蚀和保护河岸方面的作用可以产生巨大的生态和经济效益。 流体流与设备的相互作用可能相当复杂。水生植物及其产生的剪切层占据了总流域的很大一部分。水下植物可以是灵活的，耦合流体和树冠的运动。除了具有浮力之外，柔性顶篷还可以响应水流而表现出连贯的波动。由于茎的刚度会影响阻力，植被的形态也对姿态起着重要作用。阀杆刚度、叶片形状、定位及其与流动的相互作用的综合影响仍不清楚。对柔性水生植物阻力的普遍描述仍然难以捉摸。目前的研究计划是朝着更好地理解水下植被群与明渠湍流相互作用迈出的一步。 主要目标包括：（1）通过实验和数值模拟研究与柔性和刚性植被相关的流动、湍流和传输的主要特征；（2）量化柔性植被的阻力，这对于理解柔性植被至关重要。流体与设备的相互作用。 (3) 柔性和刚性植被的有限斑块的流体动力学；(4) 斑块尾迹中的湍流和相干结构的研究。 除了培训总部和影响政策制定者外，拟议的研究还将对其他温莎研究项目产生积极影响，因为为该项目组装的数值和实验工具可以成功地应用于其他调查。