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Experimental study of the flow structure of decelerating and accelerating flows under a gradually varying flume

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Abstract

The turbulence characteristics of both decelerating and accelerating flows under a gradually varying flume are investigated by using a three-dimensional down-looking acoustic Doppler velocimeter (ADV). The time-averaged velocity profiles are flatened except for the central parts, and fairly fit into logarithmic laws and those in the plane circulation under the gradual expansion are more likely to be negative. The complex secondary currents are identified under the present gradual transition attributed to the combination of driving forces induced by both the boundary configuration variation and the unbalanced turbulence: a circulation on each side of the expansion and a pair of circulations on each side of the contraction. One sees an anisotropy in the turbulence intensities, the turbulence intensities increase or level out with the flow depth except those under expansion, and the V component of the turbulence intensity typically outweighs that in the streamwise direction. Apart from the above results, the respective particular distributions of the primary Reynolds shear stresses (τ xy and τ xz) under the gradual expansion and contraction can account for the patterns of the secondary currents in this investigation.

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Authors and Affiliations

  1. State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China

    Xie-kang Wang  (王协康), Zi-jing Yi  (易子靖), Xu-feng Yan  (闫旭峰), Er Huang  (黄尔) & Xing-nian Liu  (刘兴年)

  2. Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China

    Xu-feng Yan  (闫旭峰)

Authors
  1. Xie-kang Wang  (王协康)
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  2. Zi-jing Yi  (易子靖)
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  3. Xu-feng Yan  (闫旭峰)
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  4. Er Huang  (黄尔)
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  5. Xing-nian Liu  (刘兴年)
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Corresponding author

Correspondence to Xie-kang Wang  (王协康).

Additional information

Project supported by the National Natural Science Foundation of China (Grant No. 41171016), the Sichuan Province Science and Technology Support Program (Grant No. 2014SZ0163).

Biography: WANG Xie-kang (1970-), Male, Ph. D., Professor

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Wang, Xk., Yi, Zj., Yan, Xf. et al. Experimental study of the flow structure of decelerating and accelerating flows under a gradually varying flume. J Hydrodyn 27, 340–349 (2015). https://doi.org/10.1016/S1001-6058(15)60491-7

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  • DOI: https://doi.org/10.1016/S1001-6058(15)60491-7

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