ENERGY EXCHANGE BETWEEN FLUID AND FLAPPING/BENDING STRUCTURES

流体和扑动/弯曲结构之间的能量交换

• 批准号: RGPIN-2015-05945
• 负责人: Roussinova, Vesselina
• 金额: $ 1.75万
• 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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=663785
• 关键词: ENERGY; EXCHANGE; BETWEEN; FLUID; FLAPPING; ENERGY; EXCHANGE; BETWEEN; FLUID; FLAPPING

Submerged plants with long, flexible leaves or stems are commonly found in many aquatic environments, including rivers, lakes and coastal marine waters. These plants make many significant contributions to the ecological health and water quality of their environments, including acting as sanctuary habitats, sources of food, capturing and storing particulates, reducing bed sediment erosion and turbidity. Using the engineering terminology, the aquatic plants can be defined as composite, anisotropic, viscoelastic, highly heterogeneous structures. Living in flowing waters, aquatic plants experience complex loads which are often presented by a mixture of tension, compression, bending, torsion and shear. The complex and scale dependent fluid-plant interactions are still not well understood. In particular, there are many gaps in the current knowledge related to drag-generating and drag control mechanisms.***   *Aquatic plants are typically embedded in a superposition of multi-scale boundary layers (BLs) generated by a variety of boundaries including those introduced by the plants themselves. BLs in streams and estuaries differ from the canonical boundary layers. In particular, they are often depth-limited, and they have a multi-scale structure involving effect of the bed roughness and internal effects of the plant boundaries at different scales such as patch, stem and leaf. Another important feature of natural stream BLs is a low ratio of flow depth to roughness height and therefore conventional approaches for their description, such as application of the logarithmic velocity profile, should be done with caution. ***   *In low-submergence boundary layers, aquatic plants experience drag forces imposed by the flowing water. An interesting and unexplored fluid-structure interaction is bending of multiple flexible bodies that are instead obstructing a flow. Such a situation is part of the life of aquatic plants whose morphologies are intimately related to the fluid flows they must endure to survive. Aquatic plants utilize various strategies to minimize the drag. Leaves folding and plant shape streamlining represent examples of the static reconfiguration in response to the changing velocity without involvement of waviness or flutter. Dynamic reconfiguration is a result of non-linear interactions leading to the appearance of flutter constantly changing the plant shape even at a fixed flow velocity. Although recent experimental studies have focused on the plant reconfiguration in flowing water,the theoretical and physical interpretations of this phenomenon are still not well understood. The present proposal is intended to advance the state-of-the-art modeling of the fluid structure interactions of flexible structures subjected to boundary layer flow and wave action. Experiments and numerical simulations are planned to study energy exchange between the fluid flow and flexible structures.

在许多水生环境中，通常发现淹没叶子或植物的淹没植物，包括河流，湖泊和沿海海水。这些植物为环境的生态健康和水质做出了许多重要贡献，包括充当庇护栖息地，食物来源，捕获和存储组件，减少床泥浆侵蚀和浊度。使用工程术语，可以将水生植物定义为复合材料，各向异性，粘弹性，高度异质的结构。水上植物生活在流动的水中，经历了复杂的载荷，这些负载通常是由张力，压缩，弯曲，扭转和剪切的混合物表现出来的。复杂和规模依赖性的流体植物相互作用仍然不太了解。特别是，当前与拖动和阻力控制机制相关的知识中存在许多差距。****水生植物通常嵌入由多种边界产生的多尺度边界层（BLS）的叠加中，包括植物本身引入的边界。流和河口中的BLS与规范边界层不同。特别是，它们通常是深度限制的，并且具有多尺度结构，影响床的粗糙度和植物边界在不同尺度（例如斑块，茎和叶子）上的内部效果。自然流BLS的另一个重要特征是，应谨慎进行流动深度与粗糙度高度的低比例，因此应谨慎地进行描述的常规方法，例如应用对数速度曲线。 ****在低压边界层中，水生植物经历了流动水施加的阻力。有趣且出乎意料的流体结构相互作用是弯曲多个柔性体，而这些柔性体阻塞了流动。这种情况是水生植物生命的一部分，其形态与必须忍受的流体流动密切相关。水生植物利用各种策略来最大程度地减少阻力。叶子折叠和植物形状的流线型代表了响应不断变化的速度而不会参与波浪或颤动的静态重新配置的例子。动态重新配置是非线性相互作用的结果，即使在固定流速下，也会出现颤动的出现不断变化的植物形状。尽管最近的实验研究集中在流水中的植物重新配置上，但这种现象的理论和物理解释仍未得到充分了解。目前的建议旨在推进受边界层流量和波动作用的柔性结构的流体结构相互作用的最新建模。计划进行实验和数值模拟，以研究流体流和柔性结构之间的能量交换。