Numerical Investigation of Statistical Properties of Microslips in Silos

A planar problem of filling a silo with random in diameter disks is simulated numerically. The disks are placed statically one at a time, and each added disk results in a redistribution of normal and shear forces between the disks. It is well known that in this system microinstabilities involving local slips take place. The number of disks participating in a microslide is the result of the process of self organization, i.e., finding the stable state. As opposed to the previous research when the distribution of slide sizes (called microavalanches) was measured in a variable volume of particles, as reported by Bak et al. in 1988 and Claudin and Bouchaud in 1997, in this study the number of slips is measured and it is related to a constant volume (number of particles in the system). The statistic is collected by performing 600 fillings of the silo with the total number of particles 400, and recording the needed data after the 400th particle is dropped into the silo. The simulations are performed for the fixed coefficients of friction, distribution of particle sizes, and geometry of the boundary. The results of this study show the convergence of statistical properties for the number of slips and the energy lost to stable distributions.