文档介绍：PHYSICAL REVIEW E 74, 061306 ͑2006͒
Relationship between the flow rate and the packing fraction in the choke area
of the two-dimensional granular flow
Decai Huang, Gang Sun,* and Kunquan Lu
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
͑Received 26 December 2005; revised manuscript received 6 June 2006; published 15 December 2006͒
Two-dimensional granular flow in a channel with small exit is studied by both experiments and simulations.
We first observe the time variation of the transition from dilute flow state to dense flow state by both experi-
ments and simulations. Then we obtain a relationship between the local flow rate and the local packing fraction
in the choke area by use of molecular dynamics simulations. The relationship is a continuous function rather
than a discontinuous one. The flow rate has a maximum at a moderate packing fraction and the packing fraction
is terminated at high value with negative slope. According to the relationship, four flow states—., stable
dilute flow state, metastable dilute flow state, unstable dense flow state, and stable dense flow state—are
defined for fixed inflow rate. The discontinuities and plex time variation behavior occurring in the
transition between dilute and dense flow states can be attributed to the abrupt variation through uns