Coefficient of restitution of two colliding particles in experiment and simulation

We present a study of the coefficient of restitution of two particles free to collide in a vertically shaken channel both experimentally and via simulation. Multiple cases have been investigated with the driving frequencies, f, ranging from 23 to 32 Hz and the acceleration magnitudes, Γ, from 1.78 to 3.53 g. Both the experiment and simulation results suggest the coefficient of restitution is not simply a material constant, but rather depends strongly on the impact velocity. The dependence of the coefficient of restitution on the driving frequency and amplitude are also examined. The aim of the study is to understand the mechanism of super-elastic collisions, where the coefficient of restitution is measured to be greater than unity and suggests a gaining of translational kinetic energy after collision.