Abstract
We investigate the rotational dynamics of a low-density sphere on the free surface of a vertically vibrated granular material (VGM). The dynamical behavior of the sphere is influenced by the external energy input from an electromagnetic shaker which is proportional to ε, where ε is equal to the ratio between the square of the dimensionless acceleration Γ and the square of the vibration frequency f of the container. Empirical results reveal that as the VGM transits from local-to-global convection, an increase in ε generally corresponds to an increase in the magnitudes of the rotational ωRS and translational vCM velocities of the sphere, an increase in the observed tilting angle θbed of the VGM bed, and a decrease in the time twall it takes the sphere to roll down the tilted VGM bed and hit the container wall. During unstable convection, an increase in ε results in a sharp decrease in the sphere’s peak and mean ωRS, and a slight increase in twall. For the range of ε values covered in this study, the sphere may execute persistent rotation, wobbling or jamming, depending on the vibration parameters and the resulting convective flow in the system.
Published Version
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