Thomas C C, Durian D J
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396, USA.
Phys Rev Lett. 2015 May 1;114(17):178001. doi: 10.1103/PhysRevLett.114.178001. Epub 2015 Apr 28.
We measure the fraction F of flowing grain configurations that precede a clog, based on the average mass discharged between clogging events for various aperture geometries. By tilting the hopper, we demonstrate that F is a function of the hole area projected in the direction of the exiting grain velocity. By varying the length of slits, we demonstrate that grains clog in the same manner as if they were flowing out of a set of smaller independent circular openings. The collapsed data for F can be fit to a decay that is exponential in hole width raised to the power of the system dimensionality. This is consistent with a simple model in which individual grains near the hole have a large but constant probability to precede a clog. Such a picture implies that there is no sharp clogging transition, and that all hoppers have a nonzero probability to clog.
我们根据各种孔径几何形状在堵塞事件之间排出的平均质量，测量堵塞前流动颗粒构型的分数F。通过倾斜料斗，我们证明F是在出料颗粒速度方向上投影的孔面积的函数。通过改变狭缝的长度，我们证明颗粒堵塞的方式与它们从一组较小的独立圆形开口流出时相同。F的压缩数据可以拟合为孔宽度的指数衰减，该指数以系统维度的幂次方表示。这与一个简单模型一致，在该模型中，靠近孔的单个颗粒在堵塞前有很大但恒定的概率。这样的情况意味着不存在尖锐的堵塞转变，并且所有料斗都有非零的堵塞概率。
