Three-dimensional multiscale flow structures behind a wall-mounted short cylinder based on tomographic particle image velocimetry and three-dimensional orthogonal wavelet transform

Hiroka Rinoshika, Akira Rinoshika, and Jin-Jun Wang
Phys. Rev. E 102, 033101 – Published 2 September 2020

Abstract

Three-dimensional (3D) flow structures around a wall-mounted short cylinder of height-to-diameter ratio 1 were instantaneously measured by a high-resolution tomographic particle image velocimetry (Tomo-PIV) at Reynolds number of 10 720 in a water tunnel. 3D velocity fields, 3D vorticity, the Q criterion, the rear separation region, and the characteristic of arch type vortex and tip vortices were first discussed. We found a strong 3D W-type arch vortex behind the short cylinder, which was originated by the interaction between upwash and downwash flows. This W-type arch vortex was reshaped to the M-shaped arch vortex downstream. It indicated that the head shape of the arch vortex structure depended on the aspect ratio of the cylinder. The large-scale streamwise vortices were originated by the downwash and upwash flows near the center location of W-type arch vortex. Then the 3D orthogonal wavelet multiresolution technique was developed to analyze instantaneous 3D velocity fields of Tomo-PIV in order to clarify 3D multiscale wake flow structures. The W-type shape arch vortex was extracted in the time-averaged intermediate-scale structure, while an M-shaped arch vortex was identified in the time-averaged large-scale structure. The tip vortices distributed in the time-averaged large- and intermediate-scale structures. The instantaneous intermediate-scale upwash vortices played an essential role in producing W-type head of arch structure. It was also observed that strong small-scale vortices appeared in the shear layer or near the bottom plate and most of them were contained in the intermediate-scale structures.

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  • Received 4 November 2019
  • Accepted 28 July 2020
  • Corrected 4 April 2023

DOI:https://doi.org/10.1103/PhysRevE.102.033101

©2020 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Fluid Dynamics

Corrections

4 April 2023

Correction: The affiliation indicator for the second author contained an error and has been fixed. Minor changes have been made to the Acknowledgment section.

Authors & Affiliations

Hiroka Rinoshika1, Akira Rinoshika1, and Jin-Jun Wang2

  • 1Department of Mechanical Systems Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa-shi, Yamagata 992-8510, Japan
  • 2School of Aeronautic Science and Engineering, Beijing University of Aeronautics and Astronautics, 37 Xueyuan, Haidian District, Beijing 100191, China

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Issue

Vol. 102, Iss. 3 — September 2020

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