Flow regimes of particles are predicted by means of discrete element method (DEM) in a horizontal rotating ellipsoidal drum (RED) at different rotation speeds and flattening. The macroscopic behavior of the particle flow is produced in a horizontal RED at specified rotation speed, and compared to the motion of particles in the horizontal rotating cylinder drums (RCD). Simulations indicate that there are two different flow regimes in one round with the rotating angles of the horizontal RED. The particle bed became more dilated with the increase of rotation speed. The evolution of resulting contact forces between particles and drum walls is predicted in the horizontal RED at different rotation speeds and flattening. Simulated mixing index indicates that the mixing of particles is improved at the low rotation speed and the segregation of particles is enhanced at the high rotation speed in the horizontal RED. The translational granular temperature and con temperature are calculated from simulated instantaneous velocity and displacement of particles. The predicted configurational and translational granular temperatures increase with the increase of rotation speeds and flattening in the horizontal RED. The rate of energy dissipation based on the generalized granular temperature is increased with the increase of rotation speeds in the horizontal RED. (C) 2015 Elsevier B.V. All rights reserved.