Particle Image Techniques for Measuring Instantaneous Bed Shear Stress in Open Channel Flows

被引：0

作者：

Chen Q. ^{[1
]}

Wang Z. ^{[1
]}

Duan Y. ^{[2
]}

Zhong Q. ^{[3
]}

Huang L. ^{[2
]}

Li D. ^{[2
]}

机构：

[1] School of Civil Eng., Beijing Jiaotong Univ., Beijing

[2] State Key Lab. of Hydroscience and Eng., Tsinghua Univ., Beijing

[3] College of Water Resources and Civil Eng., China Agricultural Univ., Beijing

来源：

Gongcheng Kexue Yu Jishu/Advanced Engineering Sciences | 2022年 / 54卷 / 02期

关键词：

Instantaneous bed shear stress; Open channel flow; Particle image measurement technique; Statistical characteristics;

D O I：

10.15961/j.jsuese.202100252

中图分类号：

学科分类号：

摘要：

Measurement of instantaneous bed shear stress in open channel flows is challenging but extremely important. In order to accurately measure the instantaneous bed shear stress with particle image techniques, synthesized particle images with different image and flow parameters were applied to evaluate the measurement precision of particle image velocimetry (PIV), particle tracking velocimetry (PTV), and line correlation PIV (LCPIV). The measurement precision of all techniques in the near bed region were found to be degraded towards the bed. The wall-normal height of the bed influence equals the particle image radius for PTV and LCPIV, and is not shorter than the height of the interrogation window for PIV. Outside of the bed influenced region, the measurement of PTV is unbiased and is with the highest precision when the particle image density is relatively small and the particle image diameter is medium. Therefore, PTV is more suitable for the measurement of instantaneous bed shear stress. The ability of PTV for unbiased and high precision measurement of instantaneous bed shear stress was further validated with experiments in two open channel flows with a Reynolds number of 8007 and 11462, respectively. The experiment results also indicated that the distribution of instantaneous bed shear stress in the turbulent open channel flows, with a coefficient of variation of about 0.4, is non-Gaussian. Meanwhile, both the skewness and kurtosis increase with the Reynolds number of the flow. The results provide theoretical foundation and practical reference for measuring instantaneous bed shear stress in open channel flows. Copyright ©2022 Advanced Engineering Sciences. All rights reserved.

引用

页码：122 / 132

页数：10

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