Transverse vibrations of an sphere at high combined mass-dampingparameter

In the paper are reported the first results of the experimental analysis on the transverse flowinduced vibration of an elastically mounted rigid sphere in a free surface steady flow. Experiments have been conducted in presence of three-dimensional flow field and low relative submergence, and the oscillating system characterized by low mass ratio (m*), relatively high combined mass-damping parameter (m*ζ), small amplitude (A/D < 1) and high Reynolds numbers (≈100,000). The observations and data analysis have outlined a different behavior between the test case of sphere and the results reported in literature mainly referred to cylinders concerning lock-in and hysteresis phenomena.