Observation of particle segregation in vibrated granular systems

Abstract

This paper discusses some of the parameters which affect the phenomenon of segregation in mixtures of coarse and fine particles when subjected to vibration. Initial experiments have been carried out on the motion of a single large particle through a dry granular bed consisting for the most part of a collection of particles of uniform size. A convenient range of frequencies was selected as 50–150 Hz with the range of accelerations as 1–10 g. It was found that at a constant frequency of vibration, segregation increased with increase in acceleration; however, with increasing frequencies segregation was correspondingly reduced. In general, acceleration appears to be the most critical external variable affecting segregation phenomena. The effects of size, shape and density of the large particle were also studied. It was found that for all vibratory conditions segregation increased with increase in size of the particle. A lighter particle segregates more quickly than a heavier one. However, the shapes of the particle do not appear very important. These facts may provide useful information to define the fundamental mechanism of segregation in mixtures of coarse and fine particles and other granular systems under the influence of vibrations.