粉末材料堆积的物理模型与仿真系统

Physical model and simulation system of powder packing

研究了粉末材料堆积过程仿真的物理模型和系统,并探讨了适合多种不同粒径颗粒混合堆积过程仿真的高性能计算方法.在该仿真系统中,考虑了重力、接触力、阻尼力、摩擦力和范德瓦耳斯力等多种作用力的影响,集成了多种接触力模型和阻尼模型,使其适用于三维大规模粉末材料堆积过程的计算机仿真.利用该系统对粉末材料领域中的两个典型应用进行了模拟研究.模拟了两种相同密度不同粒径颗粒(粒径比为10)的混合堆积过程.当小颗粒数为大颗粒数的300倍时,得到最大的堆积密度(体积分数)为0.82.另外,还模拟了两种不同密度相同粒径颗粒的混合堆积过程.当堆积结束时,出现了明显的分离(segregation)现象和团聚现象.所研究的物理模型和仿真系统既可用于粉末材料堆积过程研究,亦可用于普通的球形物体堆积过程的模拟研究.

The physical model and the computational system for powder packing process simulation are presented, and the high performance computing methods of simulating the random packing of mixed particles with different sizes are studied. In the simulation system the effects of gravity, contact forces, damping, friction, van der Waals force etc are take into account, therby forming several kinds of mechanical models and damping models. The system is very suitable for the three-dimensional simulation of large scale powder packing process. Finally, to demonstrate the usefulness of the simulation system, two typical applications are presented in the paper. One is to simulate the random packing of binary mixture with size ratio 10, and when the number of small particles is 300 times as large as that of big particles, the maximal packing density （volume fraction） is achieved to be 0. 824, and the other is to simulate the random mixed packing dynamics of particles with two different densities. The segregation phenomenon and clustering phenomenon take place obviously after the packing process has come to an end. The physical model and the simulation system presented in this paper are not only suitable for the study of powder packing process, but also applicable to the packing process simulation of spherical objects.