Powder Technology, Vol.362, 231-237, 2020
Two types of particle dynamics in the passive layer of a granular bed composed of irregular particles
A synchronized speckle visibility spectroscopy (SVS) has been used to simultaneously measure the granular temperatures, delta v(2), of the active and passive layers. It has been found that two-particle rearrangements are present in the passive layer. The first rearrangement, P1. occurred before the avalanche, caused by the sliding of the upper portion of the particles. The second rearrangement. P2, occurred slightly later before the surface flow, triggered by the avalanche of active layer. Comparative analysis of maximum values of two pulses in one cycle led us to conclude that the characteristics of particle motion in passive layer were mainly affected by filling degree. We believe that the particle system may have been in a transitional state at filling degree of 15 and 30%. When the filling degree is greater than 30%in a particle system, the maximum values of each period of the P2 pulses confirmed the power-law distribution. (C) 2019 Elsevier B.V. All rights reserved.