Random loose packings of polydisperse adhesive microparticles with Gaussian size distribution

Abstract

We perform a systematical numerical study on the random packings of polydisperse adhesive microspheres by means of a 3D discrete element method with adhesive contact mechanics. Empirical equations on the prediction of both bulk packing density and mean coordination number are proposed, which only depend on the normalized size variance, and an adhesion number decided by the mean particle size. On the basis of the geometrical navigation map tessellation, unique local size-topology relations for polydisperse particle system are discovered, which do not rely on the size variance. Apart from that, the radial distribution function, the angular distribution function and the distribution of surface-to-surface distance are employed to characterize the structural properties of the obtained packings. The analysis shows that the radial distribution function and the angular distribution function are not well-defined functions for multi-size particle system as the typical structural features are flattened due to the increase of size polydispersity. On the other hand, the distribution of surface-to-surface distance could be a suitable alternative for characterizing packing structures of polydisperse microparticles.