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随着计算机技术的迅猛发展,离散单元法(DEM)模拟已成为颗粒体系研究中普遍采用的方法。该方法一般采用网格划分技术来搜索邻近颗粒,以达到O(N)水平的计算复杂性。其中,网格的大小是影响模拟速度的重要因素。本研究对280mm×1060mm挡板式混合器中半径分别为R和r的2种颗粒物料的混合进行了模拟(运行在配置Intel~(?)Xeon~(?)E5430 2.66GHz处理器的工作站上),颗粒分别从混合器顶端两侧给入,汇聚成颗粒流,与挡板发生撞击并沿着挡板流动,从而达到混合的目的。研究分别考察了R=r=1mm、R=r=2mm、及R=2～3mm而r=1～2mm的3种条件和不同浓度颗粒在不同搜索网格尺寸下的运行速度。模拟结果发现,在当前的模拟体系下,单粒径颗粒及不同粒径颗粒的模拟速度由网格总数及网格内的颗粒数决定。在相同条件下,当搜索网格尺寸约为相应粒径的3倍时,计算速度较快;当颗粒的质量流量相同时,颗粒数密度与粒径的3次方成反比,因此对小颗粒的模拟计算耗时较多;另外,对颗粒质量流量在(1～10)t/h之间变化时的模拟结果表明,高流量会增加混合器中的物料浓度,从而导致模拟时间的增加。这些发现对提高颗粒物料混合的DEM模拟的效率有重要参考价值。
With the rapid development of computer technology, discrete element method (DEM) simulation has become a commonly used method in particle system research. This method generally uses the meshing technique to search for neighboring particles in order to achieve the computational complexity of O (N) level. Among them, the size of the grid is an important factor affecting the simulation speed. In this study, the mixing of two kinds of granular materials with radius R and r respectively in a 280mm × 1060mm baffle mixer was simulated (run on a workstation equipped with Intel Xeon E5430 2.66GHz processor ), The particles are fed from both sides of the top of the mixer, converged into a particle flow, collide with the baffle and flow along the baffle, so as to achieve the purpose of mixing. The research investigated the running speed of R = r = 1mm, R = r = 2mm, R = 2 ~ 3mm and r = 1-2mm, respectively, and the different particle velocity under different search grid sizes. The simulation results show that under the current simulation system, the simulation speed of single-particle particles and different particle size particles is determined by the total number of meshes and the number of particles in the meshes. Under the same conditions, the calculation speed is faster when the size of the search grid is about 3 times the corresponding size. When the mass flow rate of the particles is the same, the number density is inversely proportional to the third power of the size, The simulation results show that the high flow rate will increase the concentration of the material in the mixer and lead to the increase of simulation time. These findings have important reference value for improving the efficiency of DEM simulation of particle material mixing.