2d granular gas in Knudsen regime and in microgravity excited by vibration : velocity and position distributions

M. Hou (1) , R. Liu (1) , Y. Li (1) , K. Lu (1) , Yves Garrabos (2, 3) , Pierre Evesque (4)

1 IoP/CAS - Beijing National Laboratory for Condensed Matter Physics and Institute of Physics
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 ESEME : Équipe du Supercritique pour l'Environnement, les Matériaux et l'Espace : Équipe commune CEA-CNRS (2000-2014)
4 MSSMat - Laboratoire de mécanique des sols, structures et matériaux

Dynamics of quasi-2d dissipative granular gas is studied in microgravity condition (of the order of 10-4 g) in the limit of Knudsen regime. The gas, made of 4 spheres, is confined in a square cell enforced to follow linear sinusoidal vibration in ten different vibration modes. The trajectory of one of the particles is tracked and reconstructed from the 2hour video data. From statistical analysis, we find that (i) loss due to wall friction is small, (ii) trajectory looks ergodic in space, and (iii) distribution ρ(v) of speed follows an exponential distribution, i.e. ρ(v) exp(-v/v xo,yo) , with v xo,yo being a characteristic velocity along a direction parallel (y) or perpendicular (x) to vibration direction. This law deviates strongly from the Boltzmann distribution of speed in molecular gas. Comparisons of this result with previous measurements in earth environment, and what was found in 3d cell [1] performed in 10-2 g environment are given.

Mots clés: Granular Gas; speed distribution; ergodicity; microgravity; vibration

Domaines: Matériaux

M. Hou, R. Liu, Y. Li, K. Lu, Yves Garrabos, et al.. 2d granular gas in Knudsen regime and in microgravity excited by vibration : velocity and position distributions. Powders and Grains 2009 : proceedings of the 6th International Conference on Micromechanics of Granular Media, Jul 2009, Golden (Colorado), United States. pp.67-70, ⟨10.1063/1.3180018⟩. ⟨hal-03266232⟩