Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-23T18:04:00.301Z Has data issue: false hasContentIssue false
  • English
  • Français

A computational investigation of the instability of the detached shear layers in the wake of a circular cylinder

Published online by Cambridge University Press:  15 July 2010

MAN MOHAN RAI
MAN MOHAN RAI*
Affiliation:
NASA Ames Research Center, Moffett Field, CA 94035, USA
*
†Email address for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Cylinder wakes have been studied extensively over several decades to better understand the basic flow phenomena encountered in such flows. The physics of the very near wake of the cylinder is perhaps the most challenging of them all. This region comprises the two detached shear layers, the recirculation region and wake flow. A study of the instability of the detached shear layers is important because these shear layers have a considerable impact on the dynamics of the very near wake. It has been observed experimentally that during certain periods of time that are randomly distributed, the measured fluctuating velocity component near the shear layers shows considerable amplification and it subsequently returns to its normal level (intermittency). Here, direct numerical simulations are used to accomplish a number of objectives such as confirming the presence of intermittency (computationally) and shedding light on processes that contribute significantly to intermittency and shear-layer transition/breakdown. Velocity time traces together with corresponding instantaneous vorticity contours are used in deciphering the fundamental processes underlying intermittency and shear-layer transition. The computed velocity spectra at three locations along the shear layer are provided. The computed shear-layer frequency agrees well with a power-law fit to experimental data.

JFM classification

Instability: Instability Mathematical Foundations: Mathematical Foundations Wakes/Jets: Wakes/Jets
Type
Papers
Information
Journal of Fluid Mechanics , Volume 659 , 25 September 2010 , pp. 375 - 404
Creative Commons
This is a work of the U.S. Government and is not subject to copyright protection in the United States.
Copyright
Copyright © Cambridge University Press 2010 This is a work of the U.S. Government and is not subject to copyright protection in the United States.

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

REFERENCES

Bloor, M. S. 1964 The transition to turbulence in the wake of a circular cylinder. J. Fluid Mech. 19, 290.CrossRefGoogle Scholar
Dong, S., Karniadakis, G. E., Ekmekci, A. & Rockwell, D. 2006 A combined direct numerical simulation-particle velocimetry study of the turbulent near wake. J. Fluid Mech. 569, 185.CrossRefGoogle Scholar
Kim, J. & Choi, H. 2001 Instability of the shear layer separating from a circular cylinder. In Proceedings of the Third AFOSR International Conference on DNS/LES, Arlington, Texas.Google Scholar
Kravchenko, A. G. & Moin, P. 2000 Numerical studies of flow over a circular cylinder at ReD = 3900. Phys. Fluids 12 (2), 403.CrossRefGoogle Scholar
Matsumura, M. & Antonia, R. A. 1993 Momentum and heat transport in the turbulent intermediate wake of a circular cylinder. J. Fluid Mech. 250, 651.CrossRefGoogle Scholar
Ong, L., Wallace, J. & Moin, P. 1995 The velocity and vorticity fields of the turbulent near wake of a circular cylinder. NASA TM-110513.Google Scholar
Prasad, A. & Williamson, C. H. K. 1997 The instability of the shear layer separating from a bluff body. J. Fluid Mech. 333, 375.CrossRefGoogle Scholar
Rai, M. M. 2008 Towards direct numerical simulations of turbulent wakes. Paper 2008-0544, 46th AIAA Aerospace Sciences Meeting, Reno, Nevada.CrossRefGoogle Scholar
Rai, M. M. & Moin, P. 1993 Direct numerical simulation of transition and turbulence in a spatially evolving boundary layer. J. Comput. Phys. 109 (2), 169.CrossRefGoogle Scholar
Rajagopalan, S. & Antonia, R. A. 2005 Flow around a circular cylinder – structure of the near wake shear layer. Exp. Fluids 38, 393.CrossRefGoogle Scholar
Roshko, A. 1953 On the development of turbulent wakes from vortex streets. NACA-TN-2913, NACA-TR-1191.Google Scholar
Unal, M. F. & Rockwell, D. 1988 On vortex formation from a cylinder. Part 1. The initial instability. J. Fluid Mech. 190, 491.CrossRefGoogle Scholar
Wei, T. & Smith, C. R. 1986 Secondary vortices in the wake of circular cylinders. J. Fluid Mech. 169, 513.CrossRefGoogle Scholar
Williamson, C. H. K. 1996 Vortex dynamics in the cylinder wake. Annu. Rev. Fluid Mech. 28, 477.CrossRefGoogle Scholar

Rai Supplementary Movie

Animation shows initiation of major breakdown of upper shear layer caused by interaction between shear layer and ingested vortices. Animation also shows minor disruption of lower shear layer caused by similar interaction followed by reestablishment of quiescent state. T=6.1 through 6.9 shedding cycles, k = 8 (see Fig. 17). One frame per 40 time steps.

Download Rai Supplementary Movie(Video)
Video 13.3 MB