An air table designed to study two-dimensional disc packings: preliminary tests and first results

The authors describe in detail the characteristics of an air table designed to study two-dimensional packings of a 'large' number (up to 2500) of particles (discs). The particles are submitted mainly to hard core, and more weakly to hydrodynamic, interactions. The suspension height of a disc is studied theoretically and experimentally as a function of the air flow through the table. They also examine the dynamic properties of the system in the case of a dilute packing (evolution of the velocity of a disc and the number of collisions it has against the walls and the other discs). Then they study experimentally the spatial distribution of the discs on the table for increasing densities. The hydrodynamic interactions are hard to control and some care would be needed for further hydrodynamic studies. On the other hand, the working part of their table is sufficiently homogeneous and is appropriate to the geometrical study of densifying systems.