Wu Yongli, An Xizhong, Qian Quan, Wang Lin, Yu Aibing
School of Metallurgy, Northeastern University, 110004, Shenyang, China.
Laboratory for Simulation and Modelling of Particulate Systems, Department of Chemical Engineering, Monash University, 3800, Melbourne, VIC, Australia.
Eur Phys J E Soft Matter. 2018 Nov 27;41(11):139. doi: 10.1140/epje/i2018-11744-2.
The dynamic crystallization of cubic granular particles under three-dimensional mechanical vibration is numerically investigated by the discrete element method. The effects of operational conditions (vibration, container shape and system size) and particle properties (gravity and friction) on the formation of crystals and defects are discussed. The results show that the formation and growth of clusters with face-to-face aligned cubic particles can be easily realized under vibrations. Especially, a single crystal with both translational and orientational ordering can be reproduced in a rectangular container under appropriate vibrations. It is also found that the gravitational effect is beneficial for the ordering of a packing; the ordering of frictional particles can be improved significantly with an enlarged gravitational acceleration. The flat walls of a rectangular container facilitate the formation of orderly layered structures. The curved walls of a cylindrical container contribute to the formation of ring-like structures, whereas they also cause distortions and defects in the packing centers. Finally, it is shown that the crystallization of inelastic particles is basically accomplished by the pursuit of a better mechanical stability of the system, with decreasing kinetic and potential energies.
采用离散元方法对三维机械振动作用下立方颗粒的动态结晶过程进行了数值研究。讨论了操作条件（振动、容器形状和系统尺寸）和颗粒特性（重力和摩擦）对晶体形成和缺陷的影响。结果表明，在振动作用下，面心立方排列的颗粒簇的形成和生长很容易实现。特别是，在适当的振动下，在矩形容器中可以再现具有平移和取向有序的单晶。研究还发现，重力效应有利于堆积的有序化；随着重力加速度的增大，摩擦颗粒的有序化程度可显著提高。矩形容器的平壁有利于有序层状结构的形成。圆柱形容器的曲壁有助于环状结构的形成，但也会在堆积中心引起畸变和缺陷。最后研究表明，非弹性颗粒的结晶过程主要是通过降低系统的动能和势能，寻求更好的机械稳定性来完成的。
