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.

输送通道中淹没的植被的存在导致流动阻力增加和通道流量的降低。因此，植被经常被从通道床中取出。生物学家和生态学家已经认识到，淹没的植被可以提供广泛的重要生态系统服务。水生植被有助于减少浊度，去除养分，产生氧气并改变沉积物的运输。研究湍流与水生植被的相互作用及其在循环养分中的作用，控制侵蚀和保护河岸可以具有巨大的生态和经济利益。 流体流动植物相互作用可能非常复杂。水生植物及其产生的剪切层可以占据总流量结构域的很大一部分。淹没的植物可以柔韧，将流体和冠层的运动耦合。除了浮力外，柔性的檐篷还可以在流动时表现出连贯的挥舞。由于茎刚度，植被的形态也可以在姿势中发挥重要作用，这会影响阻力。茎刚度，刀片形状，定位及其与流动的相互作用的结合效果仍然不太了解。对柔性水生植被的阻力的普遍描述仍然难以捉摸。本研究计划是迈向更好地理解开放渠道中淹没植被与湍流的相互作用的一步。 主要目标包括：（1）通过实验和数值模拟研究流动，湍流和运输的主要特征，以及（2）量化柔性植被的阻力，这对于理解流体植物相互作用至关重要。 （3）柔性和刚性植被的有限斑的流体动力学以及（4）在斑块之后研究湍流和相干结构。 除了培训HQP和影响政策制定者外，拟议的研究还将对其他Windsor研究计划产生积极的影响，因为为该项目组装的数值和实验工具可以成功地用于其他调查中。