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Predicting the flow behavior of particles is important for the equipment design and optimization of processes and operations involving granular materials. Simulations using the discrete element method (DEM) have been used to gain insights about the granular flow, but the correct use of this technique requires knowledge about the input parameters. However, reliable measurements of these parameters remain a challenge. The purpose of this study was to test and validate experimental methodologies for determining important DEM parameters, including the coefficients of restitution and static and rolling friction, for the particle–particle and particle–wall interactions. The experimental tests were reproduced using DEM simulation to enable the identification of the best procedure for measuring each parameter. The influence of the thickness of the material on which the particles are colliding on the experimental measurement of the coefficient of restitution were quantified. It was also performed a deep statistical analysis of the simulations results using experimental design techniques to identify the significant input parameter in each measurement technique, using loose and grouped particles.

The particle dynamics in a flighted rotary drum operated with different numbers of flights and under different operating conditions was simulated by using both the Eulerian (computational fluid dynamics, CFD) and the Lagrangian (discrete element method, DEM) approaches. The simulated solid holdups in the flights as a function of the flights’ tip angular position were compared with experimental data. A systematic analysis of the computational demands of each approach was performed, as well as the impact of reducing the particle shear modulus in DEM simulations. Furthermore, the influence of the turbulence phenomenon on the particle behavior predicted by CFD simulations was also assessed. The choice of an appropriate numerical approach proved to be of great importance in the accuracy of particle dynamics prediction in a flighted rotary drum.

In the rotary dryers with flights, the drying occurs mainly in the active region where the material comes into direct contact with the air stream. The design of these flights is a complex task and studies are necessary to gain an in-depth understanding of the particle dynamics. This work aims to investigate the effects caused by angulations in flights of two and three segments on the particle dynamics, especially in the active region. The prediction of the solids flow was investigated by simulation using a Discrete Element Method (DEM) approach in an open-source software LIGGGHTS®. The simulated results were compared with experimental data using glass beads, with the rotary drum operating with 12 flights. The active region characteristics were analyzed using the responses variables: mass of solids in active phase, percentage of active region area occupied by the particles and the dispersion of the particles in the active region.

In this work, we experimentally and numerically investigated the mixing/segregation behavior of particles in an unbaffled rotary drum. We analyzed different combinations of binary mixtures that varied in density and size. We also quantified the effect of filling degree and rotational speed of the drum on the mixing index of each binary mixture. We used the discrete element method (DEM) for the simulation study, in which we determined the input parameters by both experimental measurements and calibration. The results reveal that the simulations using experimentally measured DEM input parameters had the best agreement with the experimental responses (repose angle and radial mixture). The experimental and simulation results enabled us to analyze the significant effects of filling degree and rotational speed on the granular radial and axial segregation of different binary mixtures.