Compaction of non-cohesive and cohesive granular materials under vibrations: Experiments and stochastic model

We study the time evolution of the compaction of a non-cohesive or cohesive granular material submitted to shaking through experiments and a stochastic model. Beyond well-known empirical expressions, we show that the characteristic time scales depend on the number of objects in the assembly. For a non-cohesive granular material, the compaction time scale is governed by the number of individual grains in the system. In the case of a cohesive granular material, a two-scale model (individual particles and clusters) allows one to mimic the time evolution of the compaction of an actual cohesive powder driven by horizontal. (authors)