Properties of air-fluidized granular media*

We study a 2D granular system of particles intercacting via a short-ranged potential, and thermalized homogeneously. This achieved by means of a turbulent air flow. Particles consist of 4 cm diameter ping-pong balls. We will show that, as packing fraction and air current are increased, the system can undergo transitions from gas to liquid, glass, and hexagonal phases.

The particles, placed on a metallic mesh and are subject to an uniform air flow from. This creates vortexes past the spheres, injecting energy. Air flow is adjusted so that particles remain in contact with the mesh, so that the dynamics are purely 2D. The system can be regarded as being under a stochastic white noise.

We perform several series of measurements with varying air flow intensity and density, detecting particle positions through a CV algorithm. We then carry out an analysis on single-particle trajectories and study configurational properties: pair correlation function, and order parameters.

We compare our granular temperature results against other 2D homogeneously driven granular systems.