Fundamental properties of flows in open channels with dead zone
Fundamental properties of flows in open channels with dead zone
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具有死区的明渠流动的基本特性
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
T. Hosoda
中科院分区：
文献类型：
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作者：
I. Kimura;T. Hosoda
通过实验和数值研究了具有矩形死区的明渠中非定常流动的基本行为，以阐明河岸沿岸海湾附近的质量交换机制。实验室测试结果显示了典型的流动特征，例如由于两个流动区域（主通道流动和死区）之间的混合层的剪切不稳定性而产生相干涡流以及死区中的水面振荡（seiche）。这些流动特征可以通过可变网格系统中的平面二维 (2D) 明渠流动方程进行数值再现。通过更改网格大小和常数来详细检查模型性能。将速度和深度的时间和空间变化的计算值与观测值进行比较。对计算结果的检查表明，由于塞赫和剪切不稳定性，界面处的时间速度变化可以分解为两个分量；在一次循环过程中，由不稳定引起的循环速度变化通过循环和不稳定分量之间的相互作用选择性地放大到大尺度涡流。这种选择性放大过程也可以在一系列表面流动模式的照片中检测到。
The fundamental behavior of unsteady flows in an open channel with a rectangular dead zone is investigated experimentally and numerically to clarify the mass-exchange mechanism near an embayment along a river bank. Typical flow features such as generation of a coherent vortex due to shear instability in the mixing layer between two flow regions (main-channel flow and dead zone) and water-surface oscillation (seiche) in the dead zone are shown by the findings of laboratory tests. These flow features can be reproduced numerically by plane two-dimensional (2D) open-channel flow equations in the variable grid system. Model performance was examined in detail by changing the grid size and constants. The calculated values for temporal and spatial variations in velocity and depth are compared with observed values. Examination of the calculated results shows that temporal velocity variations at the interface can be decomposed into two components due to seiche and shear instability; during one seiche, cycle-velocity variations caused by instability are amplified to the large scale vortex selectively by the interaction between seiche and instability components. This selective amplification process can be detected in a series of photographs of the surface flow pattern as well.