Vibration-induced segregation characteristics of binary pebble beds in confined containers

This paper presents the study of the segregation characteristics of bi-disperse mixed pebble beds under different confined conditions and vibration conditions by the Discrete Element Method. The Lacey index and the λ index are used to evaluate the degree of particle mixing or segregation. Results show that confined containers can suppress the segregation of the pebble beds when the top free space height is below a threshold. Further simulation reveals that this threshold of the free space height is related to the maximum bed height increment in an unconfined state and impacted by the vibration amplitude and frequency. However, the particle diameter ratio as well as the container shape and size seem to have a limited effect on the threshold. These findings are helpful to clarify the suppression effect of container confinement on the pebble bed segregation and its main resulting factors, and hence provide solutions to controlling vibration-induced segregation.