颗粒密度对旋转筒内二元颗粒体系分离的影响

摘要

The effects of particle density on the segregation of binary granular systems in a rotating drum are studied by the molecular dynamics simulation. The results show that the Brazil nut effect happens when the density of small granules is larger, whereas as the density of big granule increases, the segregation pattern is reversed and the reverse Brazil nut effect occurs. We also calculate the quantitative relationship between the segregation index and the density ratio. Finally, the mechanism of competition between percolation and condensation from Hong＇s theory is used to explain theoretically the reversion of segregation pattern.%用分子动力学的方法研究了颗粒密度对旋转筒内二元颗粒体系混合与分离的影响．当增大粒度较小的颗粒密度时，颗粒体系表现为巴西果效应，而增加粒度较大的颗粒密度时，分离状态则会发生反转，表现为反巴西果效应．进一步的研究发现二元颗粒体系的分离指数与颗粒的密度比之间存在定量的关系，并利用Hong的渗流与凝聚竞争机理理论对密度的不同产生分离状态的反转现象给予了理论解释．