Europhys. Lett.
Volume 74, Number 3, May 2006
Page(s) 384 - 390
Section General
Published online 29 March 2006
Europhys. Lett., 74 (3), pp. 384-390 (2006)
DOI: 10.1209/epl/i2005-10552-9

Temperature anisotropy in a driven granular gas

D. van der Meer1 and P. Reimann2

1  Department of Applied Physics and J. M. Burgers Centre for Fluid Dynamics University of Twente - P.O. Box 217, 7500 AE Enschede, The Netherlands
2  Department of Physics, University of Bielefeld - 33615 Bielefeld, Germany

received 2 November 2005; accepted in final form 2 March 2006
published online 29 March 2006

When smooth granular material is fluidized by vertically shaking a container, we find that the temperature in the direction of energy input always exceeds the temperature in the other directions. An analytical model is presented which shows how the anisotropy can be traced back to the inelasticity of the interparticle collisions and the collisions with the wall. For a dilute granular gas, the model compares very well with molecular-dynamics simulations. It is concluded that any non-isotropic driving of a granular gas in a steady state necessarily causes anisotropy of the granular temperature.

05.20.Dd - Kinetic theory.
05.70.Ln - Nonequilibrium and irreversible thermodynamics.
45.70.-n - Granular systems.

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