Dynamics of the breakdown of granular clusters
F. Coppex1 , M. Droz1 , A. Lipowski1,2
1 Department of Physics, University of Geneva, CH 1211 Geneva 4, Switzerland
2 Department of Physics, A. Mickiewicz University, 61-614 Poznań, Poland
Phys. Rev. E, 66, 011305 – 1-5 (2002)
Recently van der Meer et al. studied the breakdown of a granular cluster [Phys. Rev. Lett. 88, 174302 (2002)]. We reexamine this problem using an urn model, which takes into account fluctuations and finite-size effects. General arguments are given for the absence of a continuous transition when the number of urns (compartments) is greater than two. Monte Carlo simulations show that the lifetime of a cluster τ diverges at the limits of stability as τ ~ N1/3, where N is the number of balls. After the breakdown, depending on the dynamical rules of our urn model, either normal or anomalous diffusion of the cluster takes place.