Fast x-ray micro-tomography imaging study of granular packing under tapping

Owing to the high photon flux of synchrotron radiation, the exposure time is greatly reduced, and the total data-acquisition time of a tomography scan has been shortened to second level. Thus a four dimensional (3D structural and temporal) imaging technique can be utilized to capture the structural evolvement of 3D systems. Utilizing this technique, we studied the structural evolvement and particle-scale dynamics of three dimensional (3D) granular packing under tapping. We conducted a tomographic scan of the packing after each tapping, and the displacement of each particle was captured through a tracking algorithm. An averaged 3D flow field of the packing under tapping was also calculated. The major conclusion of this work is that the local particle fluctuation displacements are correlated with local packing structures, which are characterized through the size and shape of the Voronoi cells.