The multiscale modelling concept is based on a coupling between different time and length scales of the description of particle processes and is used to obtain more detailed simulations and kinetics. The simulation on lower levels in opposite to the macroscopic description allows considering the apparatus geometry and material microproperties, which play an important role.
On the lowest hierarchy scale the Discrete Element Method (DEM) and Bonded Particle Model (BPM) are used to simulate the behavior of non-spherical wet granules. The combination of BPM with the data obtained from microtomography allows to reproduce exact shape and internal structure of investigated materials. The collision dynamics of wet granules and breakage behavior of agglomerates are obtained as results from this scale.
On the microscale the coupled DEM+CFD methods are employed to investigate particle dynamics in a fluid field. The particle trajectories and fluid profile are obtained from these simulations and transferred to the mesoscale. The thermodynamic model on the mesoscale is used to calculate heat and mass transfer as well as particle wetting.
On the macroscale the Population Balance Model (PBM) is used to predict time progression of particle size distribution. The main parameters that determine kinetic (such as coalescence kernel, size-dependent growth rate, breakage rate, breakage kernel, etc.) are obtained from the lower scales. Finally, the subsystemson different scales are combined by interscale communications into one multiscale simulation environment.