Vibrated powders: Structure, correlations, and dynamics

The structure and dynamics of powders subjected to vibration are investigated by a nonsequential and cooperative computer-simulation approach in three dimensions. Starting from a microscopic model of the physics, we are able to probe independent and collective effects in the dynamics of vibrated powders, as well as in the resulting structures. In particular, we analyze the role of cooperative structures such as bridges, which are always present in reality and which cannot be formed by purely sequential processes. We look in depth at the behavior of the volume fraction and coordination number as a function of the intensity of vibration, as well as at correlation functions describing contacts between neighboring grains, also as a function of intensity. Satisfying agreement with the qualitative predictions of earlier analytic work is obtained, and a framework is laid for future investigations.