title: Bubbling in vibrated granular films.
abstract: With the help of experiments, computer simulations, and a theoretical investigation, a general model is developed of the flow dynamics of dense granular media immersed in air in an intermediate regime where both collisional and frictional interactions may affect the flow behavior. The model is tested using the example of a system in which bubbles and solid structures are produced in granular films shaken vertically. Both experiments and large-scale, three-dimensional simulations of this system are performed. The experimental results are compared with the results of the simulation to verify the validity of the model. The data indicate evidence of formation of bubbles when peak acceleration relative to gravity exceeds a critical value Γ(b). The air-grain interfaces of bubblelike structures are found to exhibit fractal structure with dimension D=1.7±0.05.
authors.affiliation: Faculty of Industrial, Mechanical Engineering, and Computer Sciences, University of Iceland, Hjardarhagi 2-6, IS-107 Reykjavik, Iceland. piroz@hi.is
authors.forename: Piroz
authors.initials: P
authors.lastname: Zamankhan