Abstract Continuum description of particle-fluid flows is of fundamental importance. In the past, various averaging methods were developed to derive local quantities directly from particle scale information. However, it is not clear if the long-sought resolution-independence of the local quantities exists. Here, using a discrete element method, a statistical analysis is conducted for a gas-solid fluidized bed of monodispersed coarse particles under various conditions. The mean free path and time are first examined with the variation of inlet gas velocity. Then, the particle motion is analyzed according to the Langevin equation and it is revealed that the motion of individual particles in the driven system follows the fluctuation-dissipation relation. Finally, the particle collisional frequency and velocity distribution are analyzed. These distributions can achieve a steady state. The particle collisional frequency distribution deviates from the Gaussian distribution noticeably at high gas velocities. These findings lead to a better understanding of particle motion in a gas-solid fluidized bed and support the seeking of resolution-independent local quantities with averaging methods.

中文翻译：

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气体流化床中单分散粗颗粒运动的统计分析

摘要 粒子-流体流动的连续描述是非常重要的。过去，开发了各种平均方法来直接从粒子尺度信息中导出局部量。然而，是否存在长期寻求的局部量的分辨率独立性尚不清楚。在此，采用离散元法，对单分散粗颗粒气固流化床在各种条件下进行统计分析。平均自由程和时间首先通过入口气体速度的变化来检验。然后，根据朗之万方程对粒子运动进行分析，揭示了被驱动系统中单个粒子的运动遵循涨落-耗散关系。最后，分析了粒子碰撞频率和速度分布。这些分布可以达到稳定状态。在高气体速度下，粒子碰撞频率分布明显偏离高斯分布。这些发现有助于更好地理解气固流化床中的粒子运动，并支持使用平均方法寻找与分辨率无关的局部量。