在淹没条件下,木桩对河流流体力学的影响

IF 2.5 3区 工程技术
Huai-jian Bao, Ping Wang, Wei-jie Wang, Yu-yan Liu, Tian-jiao Feng
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引用次数: 0

摘要

河流中的大木头会导致河道堆积,影响当地的水流结构、水生栖息地和河流地形。这对河流的生态恢复起着至关重要的作用。本文利用声学多普勒测速仪(ADV)对人工设计的工程木桩在不同流速下的六种类型的木桩下游进行了流场测量。结果表明,木桩的存在降低了尾流区的流速并增加了湍流动能,随着下游距离的增加,尾流区的流速和湍流强度逐渐恢复到上游水平。不同条件下归一化流速的最小值都位于最底层原木区域。不同流速下的归一化流速差异不大。在投影面积更大、更集中的原木卡组中,不太可能产生射流,但射流的强度会受到原木卡组物理结构(投影面积、间隙比)的影响。逻各斯堵塞后的水流分布主要受不同区域投影面积比例的影响。木塞垂直物理结构的变化对横向流分布的影响很小。不同木塞底部间隙区域(b0)的流速受木塞物理结构的影响。木塞的整体阻塞面积越大,底部缝隙区域的流速就越大。密集布置的原木堵塞底部间隙区域的流速主要受间隙比的影响。间隙区的流速会影响木塞附近沉积物的形成和沉积。然而,木桩内部结构的复杂程度对河流消能和水流衰减的影响并不大。这项研究拓宽了某些理论模型的适用范围,并探索了木桩对河流生态和河道地貌的影响。研究结果可作为河流生态恢复、木材管理和木桩施工的理论基础。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Effects of logjams on river hydrodynamics under inundation conditions

Large wood in rivers can lead to accumulations in the river channel, affecting local flow structures, aquatic habitats, and the river’s topography. This plays a crucial role in the ecological restoration of the river. This paper presents flow field measurements downstream of six types of logjams at different flow velocities using acoustic Doppler velocimetry (ADV) for artificially designed engineered logjams. The results indicate that the presence of logjams reduces the flow velocity and increases the turbulent kinetic energy in the wake region, and as the distance downstream increases, the flow velocity and turbulence intensity in the wake region gradually return to the upstream level. The minimum values of normalized flow velocity under different conditions are located in the region of the bottommost logs. The differences in normalized flow velocity at various flow rates are not significant. Jets are less likely to be generated in logjams with larger and more concentrated projection areas, but the strength of the jet is influenced by the physical structure of the logjam (projection area, gap ratio). The flow distribution behind the logjam is primarily influenced by the proportion of the projected area in different regions. Changes in the vertical physical structure of the logjam have minimal effect on the lateral flow distribution. Flow velocity in the gap area (b0) at the bottom of different logjams is influenced by their physical structure. The larger the overall blockage area of the logjams, the larger the flow velocity in the bottom gap area will be. The flow velocity in the bottom gap area of a densely placed logjam is mainly influenced by the gap ratio. The velocity of flow in the gap area can impact the initiation and deposition of sediment near the logjam. However, the internal structure complexity of the logjam does not significantly affect river energy dissipation and flow attenuation. This study broadens the applicability of certain theoretical models and explores the impact of logjams on river ecology and channel geomorphology. The findings can serve as a theoretical foundation for ecological restoration, timber management, and logjam construction in rivers.

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来源期刊
自引率
12.00%
发文量
2374
审稿时长
4.6 months
期刊介绍: Journal of Hydrodynamics is devoted to the publication of original theoretical, computational and experimental contributions to the all aspects of hydrodynamics. It covers advances in the naval architecture and ocean engineering, marine and ocean engineering, environmental engineering, water conservancy and hydropower engineering, energy exploration, chemical engineering, biological and biomedical engineering etc.
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