Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-19T06:32:23.987Z Has data issue: false hasContentIssue false
  • English
  • Français

Three-dimensional vortex structures in a cylinder wake

Published online by Cambridge University Press:  26 April 2006

J. Wu ,
J. Sheridan ,
M. C. Welsh  and
K. Hourigan
J. Wu
Affiliation:
CSIRO Division of Building, Construction and Engineering, Highett, Victoria 3190, Australia
J. Sheridan
Affiliation:
Department of Mechanical Engineering, Monash University, Clayton, Victoria 3168, Australia
M. C. Welsh
Affiliation:
CSIRO Division of Building, Construction and Engineering, Highett, Victoria 3190, Australia
K. Hourigan
Affiliation:
Department of Mechanical Engineering, Monash University, Clayton, Victoria 3168, Australia
Get access Rights & Permissions [Opens in a new window]

Abstract

The three-dimensionality of the velocity field in the wake of a circular cylinder has excited considerable interest and debate over the past decade. Presented here are experimental results that characterize the underlying vorticity field of such wakes. Using particle image velocimetry (PIV), instantaneous velocity fields were measured and from these the vorticity of the longitudinal vortices lying in the region between Kármán vortices was found. Near the saddle point, induced by the stretching of the Kármán vortices, the vorticity of the longitudinal vortices was found to be greater than the Kármán vortices themselves. Their circulation was of the order of 10% of the Kármán vortices. The high levels of vorticity result from the stretching of the longitudinal vortices, as evident in the topology of the vortices. It is shown that the longitudinal vortices are locked in phase to the KármánK vortices, effectively riding on their backs in the braid region. While only one mode of longitudinal vortex formation was observed, evidence was found of a step change in the vorticity levels at a Reynolds number of approximately 200. This is consistent with the transition point between the two modes of vortex shedding shown to exist by Williamson (1988). It had previously been proposed that the observed vortex patterns were consistent with the evolution of the longitudinal vortices from perturbations of vortex lines in the separating shear layer which experience self-induction and stretching from the Kármán vortices. Evidence is presented that supports this model.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 312 , 10 April 1996 , pp. 201 - 222
Copyright
© 1996 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adrian, R. J. 1991 Particle-imaging techniques for experimental fluid mechanics. Ann. Rev. Fluid Mech. 23, 261–304.Google Scholar
Bays-Muchmore, B. & Ahmed, A. 1993 On streamwise vortices in turbulent wakes of cylinders. Phys Fluids A 5, 387–392.Google Scholar
Bernal, L. P. & Roshko, A. 1986 Streamwise vortex structure in plane mixing layers. J. Fluid Mech. 170, 499–525.Google Scholar
Bloor, M. S. 1964 The transition to turbulence in the wake of a circular cylinder. J. Fluid Mech. 19, 290–304.Google Scholar
Gerrard, J. H. 1978 The wakes of cylindrical bluff bodies at low Reynolds number. Trans. R Phil. Soc. Lond. 288, 351–382.Google Scholar
Gonze, M. A. 1993, PhD thesis, National Polytechnic Institute, Grenoble. (Reproduced in Green, S. I. 1995 Fluid Vortices, p. 52. Kluwer).
Grant, M. L. 1958 The large eddies of turbulent motion. J. Fluid Mech. 4, 149–190.Google Scholar
Hama, F. R. 1957 Three-dimensional vortex pattern. J. Aero. Sci. 156–158.Google Scholar
Hayakawa, M. & Hussain, F. 1989 Three-dimensionality of organized structures in a plane turbulent wake. J. Fluid Mech. 206, 375–404.Google Scholar
Huang, L.-S. & Ho, C.-M. 1990 Small-scale transition in a plane mixing layer. J. Fluid Mech. 210, 475–500.Google Scholar
Jimenez, J., Cogollos, M. & Bernal, L. P. 1985 A perspective view of the plane mixing layer. J. Fluid Mech. 152, 125–143.Google Scholar
Karniadakis, G. E. & Triantafyllou, G. S. 1992 Three-dimensional dynamics and transition to turbulence in the wake of bluff objects. J. Fluid Mech. 238, 1–30.Google Scholar
Lin, J.-C., Vorobieff, P. & Rockwell, D. 1995, Three-dimensional patterns of streamwise vorticity in the turbulent near-wake of a cylinder. J. Fluids Struct. 9, 231–234.
Mansy, H., Yang, P.-M. & Williams, D. R. 1994 Quantitative measurements of three-dimensional structures in the wake of a circular cylinder. J. Fluid Mech. 270, 277–296.Google Scholar
Meiburg, E. & Lasheras, J. C. 1988 Experimental and numerical investigation of the three-dimensional transition in plane wakes. J. Fluid Mech. 190, 1–37.Google Scholar
Perry, A. E. & Fairlie, B. 1974 Critical points in flow patterns. Adv. Geophys. B14, 299–315.Google Scholar
Perry, A. E. & Steiner, T. R. 1987 Large-scale vortex structures in turbulent wakes behind bluff bodies. Part 1. Vortex formation process. J. Fluid Mech. 174, 233–270.Google Scholar
Rogers, M. & Moin, P. 1987 The structure of the vorticity field in homogeneous turbulent flows. J. Fluid Mech. 176, 33–66.Google Scholar
Roshko, A. 1955 On the development of turbulent wakes from vortex streets. NACA Rep. 1191, pp. 801–825.
Thompson, M., Hourigan, K. & Sheridan, J. 1994 Three-dimensional instabilities in the wake of a circular cylinder. Exp. Thermal Fluid Sci. (in press).Google Scholar
Wei, T. & Smith, C. R. 1986 Secondary vortices in the wake of circular cylinders. J. Fluid Mech. 169, 513–533.Google Scholar
Welsh, M. C., Soria, J., Sheridan, J., Wu, J., Hourigan, K. & Hamilton, N. 1992 Three-dimensional flows in the wake of a circular cylinder. Visualization Soc. Japan 9, 17–18.Google Scholar
Williamson, C. H. K. 1988 The existence of two stages in the transition to three-dimensionality of a cylinder wake. Phys Fluids 31, 3165–3168.Google Scholar
Williamson, C. H. K. 1989 Oblique and parallel modes of vortex shedding in the wake of a circular cylinder at low Reynolds number. J. Fluid Mech. 206, 579–627.Google Scholar
Wu, J. 1994 Three-dimensional vortical structures in the wake of a bluff body. PhD thesis, Monash University, Australia.
Wu, J., Sheridan, J., Soria, J. & Welsh, M. C. 1994a An experimental investigation of streamwise vortices in the wake of a bluff body. J. Fluids Struct. 8, 621–635.Google Scholar
Wu, J., Sheridan, J., Soria, J. & Welsh, M. C. 1994b An investigation of unsteady flow behind a circular cylinder using a digital PIV method. Laser Anemometry, Advances and Applications, ASME FED-Vol. 184, pp. 167–172.
Wu, J., Sheridan, J. & Welsh, M. C. 1994c Vortex filament simulation of the longitudinal vortices found in the wake of a bluff body. Boundary Layer and Free Shear Flows. ASME FED-Vol. 184, pp. 187–194.
Wu, J., Sheridan, J., Welsh, M. C., Hourigan, K. & Thompson, M. 1994d Longitudinal vortex structures in a cylinder wake. Phys Fluids 6, 2883–2885.Google Scholar
Zhou, Y. & Antonia, R. 1992 A study of flow properties near critical points. Eddy Structure Identification in Free Turbulent Shear Flows, IUTAM Symp., Poitiers, France, pp. IX.2.1–2.6.