The discrete element method (DEM) is well employed in computational granular dynamics. The DEM is a Lagrangian approach where individual particles are calculated based on the Newtons second law of motion. Hence, the DEM enables us to investigate the granular flow characteristics at the particle level. The calculated particle shape was often modeled to be spherical in the past studies. This is because the contact judgement is easy. The spherical particle shape often cause the difference between the simulation and experiment results. When the effect of the particle shape on the flowability cannot be neglected, the particle shape was modeled by meshes or cluster of calculated particles in the past studies. However, the calculation cost of these models became too expensive. As a result, these models could not be applied in large scale powder systems. To solve this issue we developed a DEM rotational resistance model in the previous study. The DEM rotational resistance model could simulate the actual particle whose shape was complicated, though the spherical particle was used in the simulation. On the other side, this model could not simulate the acctual recoiled particle behavior precisely. In the present study, this model is evolved by modeling the restitution. Numerical simulation and validation test were performed. The particle shape, namely, number of angles was decided based on the projected picture. Adequacy of this evolved model is validated through this study.
