NDLI: Wavelet Analysis of Reynolds Number Effect on 3-D Vorticity in a Turbulent Near Wake

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Yiu, M. W. Li, H. Zhou, Y.
Copyright Year	2003
Abstract	When Reynolds number, Re (≡U∞d/v, where U∞ is the free stream velocity, d is the cylinder diameter and v is the kinematic viscosity of the fluid), is in the range of 103 to 104, there is a large variation in the near-wake formation region in terms of the base pressure coefficient, the fluctuating lift coefficient, the vortex formation length, which have previously been connected to the generation of small-scale Kelvin-Helmholtz vortices. This work aims to investigate how this Re variation affects the three components of vorticity in terms of time-averaged and small-scale structures and also to provide a relatively complete set of 3-D vorticity data. All three components of vorticity data were simultaneously measured in the intermediate region of the turbulent wake using a multi-wire vorticity probe. It is observed that the root-mean-square (rms) values of the three vorticity components increase with Re, especially the streamwise component, which shows a large jump from Re = 5×103 to 104. At the central frequencies of f0 and 2f0, the contributions from the large-scale and intermediate-scale structures of ωzi2/(ωz2)max decreases 13% and 16% respectively as the Re. increases. However, at the central frequency of 16f0, the contribution of the small-scale structure of ωzi2/(ωz2)max dramatic suddenly 7% increase at Re = 5×103 to 104. The result suggest the generation of small-scale Kelvin-Helmholtz vortices in the spanwise structure. The effect of Re on vorticity signals, spectra, contributions from the wavelet components to the vorticity variances are also examined.
Sponsorship	Fluids Engineering Division
Starting Page	231
Ending Page	236
Page Count	6
File Format	PDF
ISBN	0791836975
DOI	10.1115/FEDSM2003-45025
e-ISBN	0791836738
Volume Number	Volume 2: Symposia, Parts A, B, and C
Conference Proceedings	ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference
Language	English
Publisher Date	2003-07-06
Publisher Place	Honolulu, Hawaii, USA
Access Restriction	Subscribed
Subject Keyword	Viscosity Turbulence Reynolds number Wake turbulence Wire Pressure Wavelets Fluids Spectra (spectroscopy) Vortices Vorticity Kinematics Wakes Signals Probes Cylinders
Content Type	Text
Resource Type	Article

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