CHINESE JOURNAL OF PHYSICS VOL. 40, NO. 4 AUGUST 2002

Effect of Hopper Angles on Jamming Probability in 2-Dimensional Hoppers

Kiwing To

Institute of Physics, Academia Sinica, Taipei, Taiwan 115, R.O.C.
(Received March 12, 2002)

We study the jamming phenomenon of granular flow in 2-dimensional (2D) hoppers of different shapes defined by their two hopper angles ($\phi_1$ and $\phi_2$ with $\phi_1 \leq \phi_2$). An automatic flipping platform is constructed to repeatedly generate the gravity flow of 700 metal disks falling through a 2D container in which the 2D hopper is installed. The jamming probability $J_{\phi_1\phi_2}(d)$, which is defined as the ratio between the number of jamming events and the number of trials, is measured as a function of the hopper opening d for different hoppers. We find that $J_{\phi_1\phi_2}(d)$ decreases with increasing d and $\phi_{1,2}$. However, for asymmetric hoppers, $J_{\phi_1\phi_2}(d)$ depends more strongly on $\phi_1$ than on $\phi_2$. For the very sharp hopper with $\phi_1=75^\circ$ and $\phi_2=90^\circ$, a very steep decrease in $J_{\phi_1\phi_2}(d)$ is observed at $d\lesssim 3$. For 3<d<3.5 a small plateau region in $J_{\phi_1\phi_2}(d)$ is found.

PACS. 45.70.Qj - Pattern Formation.
PACS. 45.70.Mg - Granular flow: mixing, segregation, and stratification.
PACS. 45.70.Vn - Granular models of complex systems; traffic flow.

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