Simple model with facilitated dynamics for granular compaction

A simple lattice model is used to study compaction in granular media. As in real experiments, we consider a series of taps separated by large enough w aiting times. The relaxation of the density exhibits the characteristic inv erse logarithmic law. Moreover, we have been able to identify analytically the relevant time scale, leading to a relaxation law independent of the spe cific values of the parameters. Also, an expression for the asymptotic dens ity reached in the compaction process has been derived. The theoretical pre dictions agree fairly well with the results from the Monte Carlo simulation . [S1063-651X(99)17810-3].