Granular Gases

Participating group members: Peter Reimann
Main cooperation partners: Detlef Lohse, Devaraj van der Meer (Physics of Fluids group at the University of Twente), Ko van der Weele

granular (a) Schematic cross section of a granular fountain exhibiting spontaneous symmetry breaking into a "cold" and a "hot" compartment and a concomitant spontaneous circular particle flow. (b) By folding out the geometry of several adjacent fountains, and adding cyclical boundary conditions, a granular ratchet is obtained with almost unchanged populations of the respective compartments and the particle currents between them.

Compared to an ordinary, molecular gas, the hallmark of a granular gas is its permanent dissipation of energy due to inelastic collisions. Hence a steady supply of energy is required to keep the gas alive, giving rise to prototypical non-equilibrium systems with many remarkable properties. Our main focus is on temperature anisotropies and on spontaneous ratchet effects arising as collective phenomena far from equilibrium when weakly dissipative granular material is kept fluidized by vertically shaking a compartmentalized container (see figure). Analytical predictions are compared both with molecular dynamics simulations and with experiments.


D. van der Meer, P. Reimann, K. van der Weele, and D. Lohse
Spontaneous Ratchet Effect in a Granular Gas
Phys. Rev. Lett. 92, 184301 (2004)
This work is illustrated by a movie (32 MB).

D. van der Meer and P. Reimann
Temperature Anisotropy in a Driven Granular Gas
Europhys. Lett. 74, 384 (2006)

D. van der Meer, K. van der Weele, and P. Reimann
Granular fountains: Convection cascade in a compartmentalized granular gas
Phys. Rev. E 73, 061304 (2006)

D. van der Meer, K. van der Weele, P. Reimann, and D. Lohse
Compartmentalized granular gases: flux model results
J. Stat. Mech., Art. No. P07021 (2007)

Last modified on 2008-09-03