  We simulate the granulation process of solid spherical particles in the
presence of a viscous liquid in a horizontal rotating drum by using molecular
dynamics simulations in three dimensions. The numerical approach accounts for
the cohesive and viscous effects of the binding liquid, which is assumed to be
transported by wet particles and re-distributed homogeneously between wet
particles in contact. We investigate the growth of a single granule introduced
into the granular bed and the cumulative numbers of accreted and eroded
particles as a function of time for a range of values of material parameters
such as mean particle size, size polydispersity, friction coefficient, and
liquid viscosity. We find that the granule growth is an exponential function of
time, reflecting the decrease of the number of free wet particles. The
influence of material parameters on the accretion and erosion rates reveals the
nontrivial dynamics of the granulation process. It opens the way to a
granulation model based on the realistic determination of particle-scale
mechanisms of granulation.
