基于离散元软件LIGGGHTS构建了球堆积床的三维随机结构模型，通过计算多孔介质的宏观阻力系数及局部孔隙率来验证模型的有效性.以典型的径向切面为研究对象，采用大涡模拟和k-ε湍流模型预测多孔介质内的湍流特性与旋涡分布规律.结果表明，随机结构模型能够预测多孔介质的宏观阻力系数及局部孔隙率.大涡模拟不仅能够描述多孔介质内部直径为 0.4~2.0mm的细小旋涡和大孔隙内的复杂旋涡结构，而且能够模拟局部孔隙内细小旋涡的产生与发展历程，以及大旋涡的拉伸、分裂直至消失的过程，这与实际情况及湍流基本理论的研究结果相符.
A three-dimensional random structure model of pellet packed bed for porous media is built based on the discrete element software of LIGGGHTS. The effectiveness of the random model has been verified by the calculation of the macroscopic flow resistance coefficient and the local porosity. A comparative study on the turbulence characteristics and vortex distribution within the porous structure has been carried out employing large eddy simulation (LES) and the conventional k-ε turbulence model. Simulation results show that the random structure model could predict the local porosity and the macroscopic resistance coefficient of the porous medium effectively. For the complex turbulent flow inside the porous structure, LES could give detailed information of the small vortices with diameter of 0.4-2.0mm within the porous structure and demonstrate the complex vortex structure in large pores of the porous medium. Besides, LES could also record the generation and development of the small vortex, and the process of stretching, splitting and disappearing of the large vortex within the local pores in detail, and the results are more consistent with the reality and the basic theory of turbulence. The LES study on turbulence characteristics in the random pellet packed bed in this paper will lay the foundation for the future simulation of filtration combustion.
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