Abstract In this paper, the combined approach of computational fluid dynamics (CFD) and discrete element method (DEM) is used to study pneumatic conveying in a horizontal pipe. A new three-dimensional modified wall roughness (WR) model and the discrete random walk (DRW) model are introduced into the CFD-DEM approach to simulate the effect of wall roughness and the random effect of turbulence on particle dispersion respectively. The interaction between particles and fluid of the pneumatic conveying in a horizontal pipe is calculated by both the one-way coupling method and the two-way coupling method. The flow characteristics of the pneumatic conveying in a horizontal pipe, including the particle velocity, the particle mass flux, and the particle trajectory are obtained by the simulations. The particle mass flux predicted by the CFD-DEM with WR-DRW is quite different with that predicted by the traditional CFD-DEM approach although the particle horizontal velocities obtained by two different approaches are similar, and the distribution of particles across the pipe cross section predicted by the CFD-DEM with WR-DRW is more uniform than that predicted by the traditional CFD-DEM approach. The accuracy of the CFD-DEM with WR-DRW is validated by the corresponding experiments from literatures. Comparing to the computational fluid dynamics - discrete phase model (CFD-DPM) without considering collision between particles, the CFD-DEM with WR-DRW developed in this work can be applied to study the pneumatic conveying in a horizontal pipe under both dilute and dense phase conditions.

中文翻译：

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水平管道气力输送的 CFD-DEM 模拟

摘要 本文采用计算流体动力学（CFD）和离散元法（DEM）相结合的方法研究水平管道气力输送。CFD-DEM 方法中引入了新的三维修正壁面粗糙度 (WR) 模型和离散随机游走 (DRW) 模型，分别模拟壁面粗糙度和湍流对颗粒分散的随机影响。水平管道气力输送中颗粒与流体的相互作用采用单向耦合法和双向耦合法计算。通过模拟得到了水平管道气力输送的流动特性，包括颗粒速度、颗粒质量通量和颗粒轨迹。CFD-DEM 和 WR-DRW 预测的粒子质量通量与传统 CFD-DEM 方法预测的粒子质量通量有很大不同，尽管两种不同方法获得的粒子水平速度相似，粒子在管道横截面上的分布使用 WR-DRW 的 CFD-DEM 预测比传统 CFD-DEM 方法预测的更均匀。CFD-DEM 与 WR-DRW 的准确性通过文献中的相应实验得到验证。与不考虑粒子间碰撞的计算流体动力学-离散相模型（CFD-DPM）相比，本文开发的带有 WR-DRW 的 CFD-DEM 可用于研究稀稠和稀稠条件下水平管道中的气力输送。相条件。