Cooperative dynamics of a group of intruders subsiding in granular media: A DEM study

Abstract

We numerically investigated the subsidence of a group of solid intruders in a randomly generated granular bed using discrete element method (DEM) in 2D and explored the cooperative behaviour of these intruders. Five intruders with a specified separation distance were placed on the surface of the granular bed and released to subside with zero impact velocity. Dynamics of the intruders was analysed. In addition, the effects of friction, boundary constraints, and the diameter and density ratio of the intruders to particles in the granular bed on the cooperative dynamics were also examined. It was found that friction and boundary constraints significantly affected the subsiding kinematics of the intruders. Most interestingly, it was shown that the intruders subside in a cooperative manner as they initially split from each other, and then move toward each other, resembling the flying pattern of a flock of birds in the air. This cooperative behaviour is in broad agreement with the experimental observations of Pacheco-Vazquez and Ruiz-Suarez (2010). © 2013 AIP Publishing LLC.