Centrifugal instability of Stokes layers in crossflow: the case of a forced cylinder wake
| Autor: | D'Adamo, Juan, Godoy-Diana, Ramiro, Wesfreid, José Eduardo |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Proc. R. Soc. A 471, 20150011 (2015) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1098/rspa.2015.0011 |
| Popis: | The wake flow around a circular cylinder at $Re\approx100$ performing rotatory oscillations has been thoroughly discussed in the literature, mostly focusing on the modifications to the natural B\'enard-von K\'arm\'an vortex street that result from the forced shedding modes locked to the rotatory oscillation frequency. The usual experimental and theoretical frameworks at these Reynolds numbers are quasi-two-dimensional, since the secondary instabilities bringing a three-dimensional structure to the cylinder wake flow occur only at higher Reynolds numbers. In the present paper we show that a three-dimensional structure can appear below the usual three-dimensionalization threshold, when forcing with frequencies lower than the natural vortex shedding frequency, at high amplitudes, as a result of a previously unreported mechanism: a pulsed centrifugal instability of the oscillating Stokes layer at the wall of the cylinder. The present numerical investigation lets us in this way propose a physical explanation for the turbulence-like features reported in the recent experimental study of D'Adamo et al. (2011). Comment: 18 pages, 13 figures. To appear in Proc. Roy. Soc. A. For supplementary video material, see http://vimeo.com/123152022 |
| Databáze: | arXiv |
| Externí odkaz: |
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