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Stabilizing effects of finite core on Kármán vortex street

Published online by Cambridge University Press:  20 April 2006

Shigeo Kida
Shigeo Kida
Affiliation:
Research Institute for Mathematical Sciences, Kyoto University, Kyoto 606, Japan
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Abstract

The stability of a vortex street consisting of two parallel rows of staggered arrangement is investigated by taking account of the effects of the finite core of the vortex. A finite stable region of the transverse-to-longitudinal spacing ratio k is found around 0·281, the value obtained by Kármán. As the core size increases, this stable region moves to larger k. The width of the stable region also changes with the core size S/l2, where S is the area of the core and l is the longitudinal spacing of the vortex street. It is null at S/l2 = 0, increases at first in proportion to the square of S/l2, takes a maximum value at S/l2 ≃ 0·08, then decreases to zero at S/l2 ≃ 0·11. For still larger values of S/l2 [gsim ] 0·11, it increases again rather rapidly. The wavenumber of the disturbance having the maximum growth rate is shown to be in complete agreement with that of a growing’ disturbance recently discovered in a vortex street behind a circular cylinder.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 122 , September 1982 , pp. 487 - 504
Copyright
© 1982 Cambridge University Press

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