  A series of accidents caused by crowd within the last decades evoked a lot of
scientific interest in modeling the movement of pedestrian crowds. Based on
discrete element method, a granular dynamic model, in which human body is
simplified as self-driven sphere, is proposed to simulate the characteristics
of crowd flow through an exit. In this model, the repulsive force among people
is considered to have an anisotropic feature, and the physical contact force
due to body deformation is quantified by the Hertz contact model. The movement
of human body is simulated by applying the second Newton's law. The crowd flow
through an exit at different desired velocities is studied and simulation
results indicated that crowd flow exhibits three distinct states, i.e., smooth
state, transition state and phase separation state. In the simulation, clogging
phenomenon occurs more easily when the velocity of desired is high and the exit
may as a result be totally blocked at a desired velocity of 1.6m/s or above,
leading to faster-to-frozen effect.
