Motion modes of granular particles in a vibrating narrow tube

Experiments are performed to investigate the motion modes of granular particles contained in a vibrating narrow tube. It is found that the motion modes strongly depend on the bed thickness and vibration acceleration. Experiments show that in a container with small lateral size, convection rolls and arching of the particles can be confined. For the bed with sufficient thickness, a condensed state of particles always exists in the lower part of the bed, even when strong vibration is applied. Once a condensed state is formed, subharmonic bifurcations of the impact of granular particles at the container bottom can be observed. Experiments reveal that the bifurcation points are independent on the bed thickness. For shallow beds, the particles may be in condensed states or in convections, depending on the particle size. For spherical particles with a narrow size distribution, an ordered packing of the particles is observed. The packing consists of a concentric array of cylindrical 'shells' of particles. In the 'shell', the particles are arrayed hexagonally.