Ciamarra Massimo Pica, De Vizia Maria Domenica, Fierro Annalisa, Tarzia Marco, Coniglio Antonio, Nicodemi Mario
Dipartimento di Scienze Fisiche, Universitá di Napoli Federico II, Coherentia-CNR, INFN, CRdC AMRA, Napoli, Italy.
Phys Rev Lett. 2006 Feb 10;96(5):058001. doi: 10.1103/PhysRevLett.96.058001. Epub 2006 Feb 8.
We present extensive molecular dynamics simulations on species segregation in a granular mixture subject to vertical taps. We discuss how grain properties, e.g., size, density, friction, as well as shaking properties, e.g., amplitude and frequency, affect such a phenomenon. Both the Brazil nut effect (larger particles on the top, BN) and the reverse Brazil nut effect (larger particles on the bottom, RBN) are found and we derive the system comprehensive "segregation diagram" and the BN to RBN crossover line. We also discuss the role of friction and show that particles which differ only for their frictional properties segregate in states depending on the tapping acceleration and frequency.
我们展示了对受垂直敲击的颗粒混合物中物种分离的广泛分子动力学模拟。我们讨论了颗粒特性，例如尺寸、密度、摩擦力，以及振动特性，例如振幅和频率，如何影响这种现象。我们既发现了巴西坚果效应（较大颗粒在顶部，即BN），也发现了反向巴西坚果效应（较大颗粒在底部，即RBN），并得出了系统的综合“分离图”以及从BN到RBN的转变线。我们还讨论了摩擦力的作用，并表明仅摩擦特性不同的颗粒会根据敲击加速度和频率在不同状态下发生分离。
