No abstract

Abstract. Particle percolation in a vibrated bed is investigated by means of discrete element method (DEM). It is found that under some vibrational conditions, percolation becomes unsteady with the percolation velocity fluctuating in a wide range. This happens when dimensionless vibrational velocity, V b (A.(2ʌf)/ඥ݃‫,)ܦ‬ is in a certain range, where A is the vibrational amplitude, f is the vibrational frequency, g is the gravitational acceleration and D is the diameter of large particles. The unsteady particle percolation in this range has been analysed on a particle scale, which reveals that V b (in the certain range) can favour the crystallization in the vibrated bed, which significantly decreases the particle percolation velocity. Such crystallizations occasionally happen, leading to the unsteady percolation behaviour.