A surface instability of granules under vibration in partitioned containers

This paper describes a surface instability of vibrated granules contained in rectangular vessels. The vessels are partitioned in two equal sections by a vertical plate whose lower end is placed at a certain distance from the vessel base. The free surfaces of granules in two sections, initially at an equal level, start to move when submitted to vertical vibrations, and stabilize at different levels. Measurements are made of the pressure at the bottom of each of the partitioned beds, which reveals the underlying mechanism of the surface instability. Computer simulations are performed to show microscopic structures of this surface instability.