Effects of coefficient of friction and coefficient of restitution on static packing characteristics of polydisperse spherical pebble bed

The effects of the coefficient of friction and coefficient of restitution on the static packing characteristics of a polydisperse spherical pebble bed are numerically investigated using the discrete element method. Several important static packing characteristics under different coefficients of friction and restitution are presented and discussed. The results show that the coefficients of friction and restitution impose opposite effects on the packing heights and global packing factor. Neither the coefficient of friction nor restitution affected the oscillation width of the wall, whereas their effects are primarily reflected in the oscillation amplitude of the radial local packing factor and the axial local packing factor distribution at the top of the pebble bed. In both the contact force distribution and coordination number distribution, a left-shifted phenomenon appearing as the coefficient of friction occurred, and only the magnitude of the maximum frequency is affected when the coefficient of restitution changed from 0.1 to 0.9. In all simulation cases, the effects of the coefficients of friction and restitution are similar to that of cross-impact. (C) 2021 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.