Wall-attached structures over a traveling wavy boundary: Turbulent velocity fluctuations

Li-Hao Wang, Chun-Xiao Xu, Hyung Jin Sung, and Wei-Xi Huang
Phys. Rev. Fluids 6, 034611 – Published 16 March 2021

Abstract

The wall-attached structures of velocity fluctuations over a traveling wavy boundary are explored here by performing large eddy simulation (LES) at a moderate Reynolds number (Reτ1000). The wave slope is ak=0.1, where a is the wave amplitude and k is the wave number. The prescribed wave age is c/u*=2, where c is the wave phase speed and u* is the friction velocity. For comparison, the results of a LES over a smooth wall are also discussed. The wall-attached structures are self-similar with respect to their heights, and in particular the population density of their streamwise components scales inversely with their heights, which is reminiscent of a hierarchy of attached eddies. The wall-attached structures in the flow over the traveling wavy boundary retain geometric self-similarity; however, their streamwise length scale is decreased by the wavy boundary while their spanwise length scale is increased. By conditionally averaging the streamwise velocity fluctuations within the wall-attached structures, the reconstructed streamwise turbulent intensity was found to exhibit logarithmic behavior. The turbulent intensity carried by the small-scale wall-attached structures in the near-wall region is weakened by the traveling wavy boundary, while that of the large-scale wall-attached structures in the outer region is enhanced. The streamwise velocity corresponding to the highest uniform momentum zone for the large-scale wall-attached structures in the presence of the wavy boundary is larger than that for the smooth wall.

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  • Received 20 August 2020
  • Accepted 16 December 2020

DOI:https://doi.org/10.1103/PhysRevFluids.6.034611

©2021 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Authors & Affiliations

Li-Hao Wang1, Chun-Xiao Xu1, Hyung Jin Sung2, and Wei-Xi Huang1,*

  • 1Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
  • 2Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea

  • *hwx@tsinghua.edu.cn

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Vol. 6, Iss. 3 — March 2021

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