  Studies on random packing of bidispersive particles have shown that such
systems can capture the underlying behavior of more complex phenomena found in
physics and materials engineering. In industry, bidispersive particles are used
to allow the increase of density and fluidity of the formed compounds. The
understanding of the dynamics of these processes is therefore of great
theoretical and practical interest. In this paper, we perform molecular
dynamics (MD) simulations to study the packing process of particles with binary
size distribution. Samples with different particle population densities ($p$)
as well as particle size ratios ($\lambda$) have been assessed. The initial
positions of five thousand non-overlapping particles are assigned inside a
confining rectangular box. After that, the system is allowed to settle under
gravity towards the bottom of the box. Both the translational and rotational
movements of each particle are considered in the simulations. In order to deal
with interacting particles, we take into account both the contact and
long-range cohesive forces. The normal viscoelastic force is calculated
according to the nonlinear Hertz model, whereas the tangential force is
calculated through an accurate nonlinear-spring model. Assuming a molecular
approach, we account for the long-range cohesive forces using a
Lennard-Jones(LJ)-like potential. The packing processes are studied assuming
different long-range interaction strengths. We carry out statistical
calculations of the different quantities studied including packing density,
radial distribution function and orientation pair correlation function.
