Brazil nut effect in annular containers

This paper investigates the motion of particles between two co-axial cylinders which are subjected to a sinusoidal vertical vibration. We measure the rising time of a large intruder from the bottom of the container to the free surface of the bed particles and find that the rising time as a function of intruder density decreases to a minimum and then increases monotonically. The result is qualitatively opposite to the previous findings in experiments using cylindrical containers where a maximal instead of minimal rising time in the small-density regime was found. The experimental results suggest that the topology of the container plays an important role in the Brazil nut effect