Determination Method of Coefficients of Particle and Rolling Friction in Distinct Element Method

A new method to determine both the coefficients of particle and rolling friction in distinct element method (DEM) was proposed. The coefficients are two of the most important parameters which have great effect on particle behavior in DEM. However, it is difficult to determine the values of the coefficients, which is applicable to multiple behaviors, from an experiment. We proposed the method to determine the two coefficients uniquely so that two indicators correspond to experimental results. As the indicators of static and dynamic behaviors, the angle of repose and the discharge flow rate were adopted, respectively. The values of the coefficients which can represent both static and dynamic behaviors of particles were determined by means of the method. The particle behavior in a rotating drum at three different rotational speed was simulated by using the determined coefficients in order to verify the applicability of them to dynamic behavior of particles under various conditions. The simulated behaviors for spherical particles corresponded to the experimental ones. The determined coefficients by means of the proposed method could be applied to the behavior of spherical particles at all of the rotational speeds. On the other hand, the simulated behaviors for irregularly shaped particles did not correspond to the experimental ones, in particular at higher rotational speed. It would be because the rolling friction of irregularly shaped particles depends on the particle velocity in a rotating drum.