巴西果效应分离过程的计算颗粒力学模拟研究

采用离散单元模型对巴西果问题进行了模拟研究，采用本数学模型可以准确地预测出垂直机械振动导致的不同大小颗粒的分离现象.分析了影响振动床内颗粒分层的因素，讨论了振动频率、振动幅度等参数对分层的影响，发现振动频率和振动幅度会对分离效果造成较大的影响.当振动频率或振动幅度较小时，颗粒整体分离效果都较差，但分离的稳定性较好，当振动频率或振动幅度较大时，整体分离效果仍然较差，同时分离的稳定性也较差，振动分离过程中存在一个频率和振幅适中的最优操作点. 关键词： 分层 振动 模式形成 离散单元方法

Discrete element simulation of the segregation in Brazil nut problem

The segregation of the binary granular mixture in Brazil nut problem was simulated by using discrete element model. The influences of the frequency and the amplitude of the vibration on the segregation are discussed. The simulation results show that the segregation between big and small particles can be predicted accurately. When the frequency or the amplitude of the vibration is low, the final segregation efficiency is low, but the segregation is quite stable. When the frequency or the amplitude of the vibration is high, the final segregation efficiency is still low, but the segregation is unstable. An optimum operating point with a moderate frequency and a moderate amplitude of the vibration exists in the process of segregation in Brazil nut problem.