Two types of oscillation in unequally compartmentalized granular gases

Intruder-induced asymmetry in compartmentalized granular gases

The clustering behavior of a compartmentalized monodisperse granular gas with the addition of one heavy intruding particle is investigated experimentally. Depending on the number of particles, the presence of a heavy intruder leads to three population states: a homogeneous state, an expelled clustering state, and a fully clustering state. These states are found to be consistent with the clustering of a purely monodisperse granular gas in an asymmetric compartmentalized structure. We obtain an exact relation between the size of an intruder and the elevation of the compartment bottom. This relation quantifies the particle-expelling ability of a heavy intruder, and suggests that the one-intruder system is a type of asymmetric system with an intruder-size-related asymmetrical index ξ. Under the framework of the flux model, a ξ-associated Ξ function is proposed to quantitatively reproduce the experimental results.

Stop and restart of granular clock in a vibrated compartmentalized bidisperse granular system

This paper studies a bidisperse granular mixture consisting of two species of stainless steel spheres in a vertically vibrated compartmentalized container. The experiments show that with proper vibration acceleration, the granular clock stops when horizontal segregation of the large spheres residing in the far end from the barrier wall occurs. When the segregation is broken, the granular clock restarts. We present the phase diagrams of vibration acceleration versus container width and small particle number, which exhibits three different regions, namely, clustering state, stop-restart of the granular clock, and the granular clock. A generalized flux model is proposed to reproduce the phenomenon of stop and restart of the granular clock.