Aspect ratio influence on the vortex induced vibrations of a pivoted finite height cylinder at low Reynolds number

Abstract

The effect of the aspect ratio on the vortex induced vibrations (VIV) of a pivoted finite length circular cylinder is investigated. A fixed value of the Reynolds number Re = 100 with four values of the aspect ratio AR=2, 3, 5, 7 is considered. Different values of the reduced velocity ur* in the range 2≤ur*≤11 were used for each AR value with a fixed value of the reduced mass mr*=5. Results on the oscillatory response of the cylinder, hydrodynamic forces, and wake structures are reported. In order to compare the VIV of the different length cylinders, the displacement of the center of mass (which coincides on each case) was analyzed. It is found that the maximum oscillation amplitudes, the extent of the synchronization region, and the wake structures are influenced by the aspect ratio. Also, a steady symmetrical flow is obtained for the small AR=2, 3 cases with relatively low values of ur*, which is found to be unstable when increasing ur*.