In this study, the Euler-Lagrange method based DEM(discrete element method)is used to simulate the unsteady gas-solid two phase flow in the initial stage of three-dimensional bubbling fluidized bed to break the bottle-neck in the Euler-Euler model in which the force of particle collisions is not taken into account. Based on experimental observations made by high speed photographic technique in the initial stage of flow in the fluidized bed, a comparison is conducted between experiment and simulation in terms of changes in bed height, bubble size and particle phase motion characteristics. In the initial stage, the predicted results are in good agreement with the experimental data, particularly, the predicted height of bed and the shape of bubbles are basically the same as the measurements. Unfortunately, at a time moment near the bubble breakup, the predicted bubble diameter and height of bed are smaller than the experimental measurements. However, from the point of view of both fluid flow pattern and particle motion trajectory, DEM can solve the dense two-phase flow accurately, but also can describe the dynamic characteristics of a gas solid fluidized bed. The results presented in this study have important significance in guiding engineering practice.
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