Turbulent shear flow without vortex shedding, Reynolds shear stress and small-scale intermittency
Author(s)
Steiros, K
Obligado, M
Braganca, P
Cuvier, C
Vassilicos, JC
Type
Journal Article
Abstract
This work presents an experimental investigation of the effects of vortex shedding suppression on the properties and recovery of turbulent wakes. Four plates, properly modified so that they produce different vortex shedding strengths, are tested using high speed particle image velocimetry and hot-wire anemometry, and analysed using spectral proper orthogonal decomposition, mean-flow linear stability analysis and various turbulence statistics. When present, vortex shedding is found to exhibit a characteristic frequency that scales with the mean shear, providing a link between the mean flow and the main turbulent motion. To achieve full suppression of shedding, we combine the effects of porosity and fractal perimeter. The mean shear is then decreased to the point where the flow becomes convectively unstable and shedding vanishes. In that case, the onset of self-similarity is delayed, compared with the case with vortex shedding, and appears after another large-scale structure, the secondary vortex street, emerges. It is also found that both large- and small-scale intermittency are starkly reduced when shedding is absent. A simple theoretical representation of the wake dynamics explains the evolution of the wake properties and its connection to the coherent structures in the flow.
Date Issued
2025-01-10
Date Acceptance
2024-11-26
Citation
Journal of Fluid Mechanics, 2025, 1002
ISSN
0022-1120
Publisher
Cambridge University Press
Journal / Book Title
Journal of Fluid Mechanics
Volume
1002
Copyright Statement
© The Author(s), 2025. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/ licenses/by/4.0), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
License URL
Subjects
CYLINDER
INSTABILITY
intermittency
Mechanics
Physical Sciences
Physics
Physics, Fluids & Plasmas
POROUS BODY
Science & Technology
Technology
vortex streets
WAKE
Publication Status
Published
Article Number
A51
Date Publish Online
2025-01-09