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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Flow transition behind a heated cylinder

Get access (open in a dialog) DOI: 10.1615/IHTC12.3260
15 pages

Abstract

For more then a century the wake flow behind a cylinder was the subject of study in many investigations. Most of the attention focussed on the first instability and the transition towards 3D for the flow around an unheated cylinder. The wake stability for a heated cylinder has until now received very little attention compared to the forced convection case. After a review of the literature on the wake flow behind an unheated and heated cylinder, in this paper the 2D wake behaviour and the 3D flow transition behind a heated cylinder is described. In the analysis performed, the Reynolds number is set around ReD = 100 and the Richardson number is varied between RiD = 0 (forced convection case) and RiD = 1.5 (mixed convection case). From the results it is seen that for a relatively small heat input (RiD < 1) the vortex street undergoes a negative deflection, i.e. downwards, caused by a strength difference between the upper and lower vortices which, on its turn, is induced by baroclinic vorticity production. This strength difference also results in a rotational drift of the lower vortex around the upper vortex. For a higher heat input (RiD > 1) an early 3D transition is observed. Mushroom-type structures appear on top of the upper vortex row. This flow transition is initiated by the occurrence of 3D flow structures at the rear end of the cylinder.