Abstract: Discrete element software LIGGGHTS is introduced to reproduce the forming process of sphere packed bed by gravity， and a 3D random geometric model similar to the actual accumulation structure is presented. Two ordered models， the in-line packed model and the staggered packed model， are also established to contrast with the random packed model. CFD software of Fluent 14.0 is employed to study the turbulence flows in the packed bed. The effectiveness of the random model is validated by analysis of the macroscopic pressure drop and the resistance coefficient， and the velocity field and the turbulence parameters of the three structures are predicted and discussed. Simulation results show that the macroscopic resistance coefficient and the macroscopic pressure drop of the random packed bed model are consistent with the classical formula of Ergun， with maximum relative error less than 6%. Compared with the orderly packed bed， the random packed model is characterized with more homogeneous velocity field， larger tail vortex size， stronger disturbance and extremely larger turbulence dissipation.

Key words: porous medium, packed bed, random structure, velocity field, turbulence characteristic