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

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.

具有长而柔韧的叶子或茎的沉水植物常见于许多水生环境中，包括河流、湖泊和沿海海水，这些植物对其环境的生态健康和水质做出了许多重大贡献，包括充当保护区栖息地、水源。使用工程术语，水生植物可以被定义为生活在流动水中的复合的、各向异性的、粘弹性的、高度异质的结构。水生植物承受着复杂的载荷，这些载荷通常由拉力、压缩力、弯曲力、扭转力和剪切力混合而成，这种复杂且与尺度相关的流体与植物的相互作用仍然没有得到很好的理解。特别是，目前的相关知识还存在许多空白。 ***    *水生植物通常嵌入由各种边界产生的多尺度边界层 (BL) 的叠加中，包括由植物本身在溪流和河口引入的不同边界层。从特别是，它们通常是深度有限的，并且具有多尺度结构，涉及不同尺度（例如斑块、茎和叶）的植物边界的影响和内部影响。自然河流 BL 的水流深度与粗糙度高度之比较低，因此应谨慎使用传统的描述方法（例如应用对数速度剖面）***   *在低淹没边界层、水生植物中。一种有趣且未经探索的流体-结构相互作用是阻碍流动的多个柔性体的弯曲，这种情况是水生植物生命的一部分，其形态与流体流动密切相关。水生植物利用各种策略来最大限度地减少阻力，并且植物形状流线型代表了响应变化的速度的静态重新配置的例子，而动态重新配置是一种动态重新配置。尽管最近的实验研究集中在流水中的植物重构，但这种现象的理论和物理解释仍然不充分。目前的提议旨在推进对边界层流动和波浪作用下的柔性结构的流体结构相互作用进行最先进的建模，计划通过实验和数值模拟来研究流体流动和波浪作用之间的能量交换。灵活的结构。