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Three-dimensional transition of a water flow around a heated cylinder at ${{Re\,{=}\,85}}$ and ${{Ri\,{=}\,1.0}}$
Published online by Cambridge University Press: 05 October 2006
Abstract
The three-dimensional flow transition behind a heated cylinder subjected to a horizontal flow (water is used as the working fluid; $Pr\,{\simeq}\,7$) at a Reynolds number $\hbox{\it Re}\,{=}\,85$ and a Richardson number $\hbox{\it Ri}\,{=}\,1.0$, manifests itself in the far wake as escaping mushroom-type structures from the upper vortices. The origin of the escaping mushroom-type structures lies in the generation of streamwise vorticity in the near wake, which is described as a cyclic process. In the presence of a spanwise temperature gradient in the near wake, streamwise vorticity is generated, which results from baroclinic vorticity production. Owing to these streamwise vorticity regions, low-speed flow will move upwards at so-called in-plume positions resulting in high- and low-speed streaks in the upper half of the wake. Next, ‘transverse’ vorticity is generated by the spanwise gradients in the streamwise velocity component, resulting in counter-rotating vortices directly behind the cylinder. These vortices lead to high- and low-temperature regions in the spanwise direction and the process repeats itself.
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- © 2006 Cambridge University Press
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