基于非解析计算流体力学和离散单元法的大颗粒在流场中的高效率运动模拟

为实现占据多个流体网格的大颗粒在流场中运动的仿真,基于计算流体力学和离散单元法耦合(computational fluid dy namics-discrete element mothod,CFD-DEM),提出了一种新的数值方法.使用黏结颗粒模型将大颗粒近似表示为多个小球形颗粒黏结而成,基于非解析CFD-DEM方法计算流体对每个小球颗粒的作用力,将所有小球颗粒运动参数的平均值用于描述整个黏结颗粒的运动状态.通过黏性流体中球形大颗粒的沉降运动模拟,比较仿真结果与相关实验数据,结果表明:该方法不仅能准确模拟球形大颗粒的沉降运动,而且与浸没边界法相比计算效率更高.与传统的解析CFD-DEM方法相比,此方法还可以方便且准确地模拟三维情况下非球形大颗粒在流场中的运动.

Efficient simulation about the motion of large particles in fluid based on unresolved CFD-DEM

In order to realize the simulation of the motion of large particles occupying multiple fluid grids in the fluid, based on the coupling of computational fluid dynamics and discrete element method (CFD-DEM), a new numerical method is proposed. Using the bonded-particle model to approximate a large particle as multiple small spherical particles bonded together, the force of the fluid acting on each small spherical particle can be calculated based on the unresolved CFD-DEM method, and the average values of the motion parameters of all small spherical particles are used to describe the motion state of the entire bonded-particle. By simulating the settlement motion of large spherical particles in the viscous fluid and comparing the simulation results with related experimental data, the results show that this method can not only accurately simulate the settlement motion of large spherical particles, but also has higher computational efficiency compared with the immersed boundary method. And compared with the traditional resolved CFD-DEM method, this method can conveniently and accurately simulate the motion of large non-spherical particles in the fluid in three dimensions.