Particle interactions in a dense monosized granular flow

Simulations of bounded dense sheared granular flows were performed to investigate multi-phase flow phenomena, in particular the behavior of the ordered phase. In the absence of gravity, collapse of the granular structures was found to occur for a wide range of shear rate, as evidenced by the disappearance of the signature of the ordered structure in the wall normal stress signal. However, normal stress signals matching those detected in recent experiments were obtained for a system whose dynamics were collision-dominated rather than friction-dominated. Moreover, the system was found to exhibit a similar flow behavior in the presence of gravity. The stress signals were analyzed using wavelet transforms, which indicated the existence of stick–slip dynamics, characterized by harmonic frequencies. It is shown that these observations might elucidate the origin of stick–slip dynamics in the system, which experienced instability due to gravitational compactification at shear rates below a certain critical value.