Third M.I.T. Conference on Computational Fluid and Solid Mechanics June 14–17, 2005  

Wake mode development for flow past low aspect ratio cylinders

G.J. Sheard*, M.C. Thompson, K. Hourigan
Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Department of Mechanical Engineering, Monash University, VIC 3800, Australia
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ABSTRACT
The side-forces imparted on a short cylinder with free hemispherical ends are investigated numerically in comparison to the flow past sphere.

A time-dependent wake flow initiates both axial and transverse modes of oscillation in the wake of the cylinder, whereas for a sphere oscillation is only observed in one plane. The relationship between these modes to the first-occurring Hopf mode in the wake of a sphere is considered.

The bifurcations in the cylinder wake are analyzed with the Landau equation. It is found that the transitions occur through supercritical bifurcations, and the bifurcation process is initiated by a transverse mode even at short length ratios.

Keywords:  Sphere wake; Cylinder with hemispherical ends; Planar symmetry; Computational fluid dynamics; Spectral-element method; Hopf transition; Reynolds number
* Corresponding author. Tel.: + 61 (3) 9905 1182; Fax: + 61 (3) 9905 3807; E-mail: Greg.Sheard@eng.monash.edu.au