A Global Stability Analysis of the Wake behind a Rotating Circular Cylinder

A new high resolution approach based on spectral element method is proposed to analyse the complex global stability for the non-parallel flow passing a rotating and translating circular cylinder. The studies presented here predict the variation of Strouhal number S_t as the spin parameter α increases from 0.0 to 1.4, for the Reynolds number R_e=60. The direct numerical simulation shows a small increase of vortex shedding frequency at α<1.1, and a slight decrease as α approaches the critical spin parameter α=1.37. The trend of variation of eigen-frequency with α obtained by linear stability analysis is opposite to those obtained by direct numerical simulation for R_e=60, although they achieve the same frequency at the onset of vortex shedding.