Majmudar T S, Sperl M, Luding S, Behringer R P
Department of Physics, Duke University, Box 90305, Durham, North Carolina 27708, USA.
Phys Rev Lett. 2007 Feb 2;98(5):058001. doi: 10.1103/PhysRevLett.98.058001. Epub 2007 Jan 29.
Recent simulations have predicted that near jamming for collections of spherical particles, there will be a discontinuous increase in the mean contact number Z at a critical volume fraction phi(c). Above phi(c), Z and the pressure P are predicted to increase as power laws in phi-phi(c). In experiments using photoelastic disks we corroborate a rapid increase in Z at phi(c) and power-law behavior above phi(c) for Z and P. Specifically we find a power-law increase as a function of phi-phi(c) for Z-Z(c) with an exponent beta around 0.5, and for P with an exponent psi around 1.1. These exponents are in good agreement with simulations. We also find reasonable agreement with a recent mean-field theory for frictionless particles.
最近的模拟预测，对于球形颗粒集合体，在接近堵塞状态时，临界体积分数φ(c)处的平均接触数Z会有不连续增加。高于φ(c)时，预计Z和压力P会随着φ - φ(c)的幂律增加。在使用光弹性圆盘的实验中，我们证实了在φ(c)处Z会快速增加，且高于φ(c)时Z和P呈现幂律行为。具体而言，我们发现Z - Z(c)作为φ - φ(c)的函数呈幂律增加，指数β约为0.5，P的指数ψ约为1.1。这些指数与模拟结果高度吻合。我们还发现与最近关于无摩擦颗粒的平均场理论有合理的一致性。
