Transverse vibrations of an sphere at high combined mass-damping parameter

In the paper are reported the first results of the experimental analysis on the transverse flow-induced 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*), small amplitude (A/D < 1) and high Reynolds numbers (100,000). The observations and data analysis have out-lined 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.