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Ordered and chaotic vortex streets behind circular cylinders at low Reynolds numbers

Van Atta, C. W. and Gharib, M. (1987) Ordered and chaotic vortex streets behind circular cylinders at low Reynolds numbers. Journal of Fluid Mechanics, 174 . pp. 113-133. ISSN 0022-1120. https://resolver.caltech.edu/CaltechAUTHORS:20130916-160630938

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Abstract

We report some experiments undertaken to investigate the origin of ordered and chaotic laminar vortex streets behind circular cylinders at low Reynolds numbers. We made simultaneous measurements of near wake longitudinal velocity and cylinder lateral vibration amplitude spectra for cylinder Reynolds numbers in the range from 40 to 160. For a non-vibrating cylinder the velocity energy spectra contained only a single peak, at the Strouhal frequency. When the cylinder was observed to vibrate in response to forcing by the vortex wake, additional dominant spectral peaks appeared in the resulting ‘ordered’ velocity spectra. Cylinder vibrations too small to be noticed with the naked eye or from audible Aeolian tones produced a coupled wake-cylinder response with dramatic effects in hot-wire and cylinder vibration detector signals. The velocity spectra associated with these coupled motions had dominant peaks at the Strouhal frequency fs, at a frequency fc proportional to the fundamental cylinder vibration frequency, and at sum and difference combinations of multiples of fs and fc. In windows of chaos the velocity spectra were broadened by switching between different competing coupling modes. The velocity spectra were very sensitive to the nature of the boundary conditions at the ends of the cylinder. Our measurements strongly suggest that the very similar regions of ‘order’ and ‘chaos’ observed by Sreenivasan and interpreted by him as transition through quasi-periodic states in the sense of the Ruelle, Takens, and Newhouse theory were also due to aeroelastic coupling of the vortex wake with cylinder vibration modes.


Item Type:Article
Related URLs:
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http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=392712PublisherArticle
http://dx.doi.org/10.1017/S0022112087000065 DOIArticle
Additional Information:© 1987 Cambridge University Press. Received 21 August 1985 and in revised form 22 May 1986. We wish to thank Mr M. Khazra for assistance with some of the experiments, Dr J. Starrett for his design of the strain gauge beam, and Professor K. R. Sreenivasan for a preprint of his paper and several useful discussions. The work was partially supported by NSF Grant OCE 85-11290 and the Defense Advanced Research Projects Agency University Research Initiative Program.
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NSFOCE 85-11290
Defense Advanced Research Projects Agency (DARPA) University Research Initiative ProgramUNSPECIFIED
Record Number:CaltechAUTHORS:20130916-160630938
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130916-160630938
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41352
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Sep 2013 19:57
Last Modified:03 Oct 2019 05:48

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