Oscillatory granular flows

An experimental device has been used to examine the behavior of granular materials under vertical, horizontal and combined bi-axial vibrations. Different container geometries were used with glass spheres, millet and lentils as granular media. Frontal and lateral visualization of the flow was made possible with high-speed video cameras. Four different phenomena: heaping, arching small amplitude surface waves and large amplitude surface waves were found. The onset of these depend basically on two parameters: the dimensionless acceleration and the dimensionless depth of the vibrating bed. Comparison was made between experiments and numerical predictions based on molecular dynamics. The numerical solution agrees well with all the experimental observations.