VIV response of a suspended sphere nearby the critical Reynolds number

The Vortex-Induced Vibration of a sphere connected to a flexible beam is investigated in air for Reynolds numbers including the critical value. For this value (ReC =3e5 ), wake disorganisation is expected in a static configuration. This fundamental fluid-structure interaction characterised by an axisymmetric configuration leads to vibrations in the lateral and longitudinal directions. Similarly to the well-known circular cylinder, a lock-in phenomenon will take place due to the effect of the motion of the body on the shedding process. An experimental aeroelastic model is designed, instrumented and tested in the wind tunnel of University of Liège. The objective is twofold: (i) solve a practical wind-engineering problem (a spherical suspended streetlight) and (ii) propose a fundamental investigation of the VIV of a smooth sphere for sub-critical and critical Reynolds numbers.