(99b) DEM Simulation of Aggregates Formation in Granular Shear Flow

DEM (Discrete Element Method) simulation of aggregates formation in two-dimensional cohesive granular shear flow was performed to investigate the physics of aggregates formation in granular flow and numerical models to express aggregation. JKR[1] model and a linear-spring-dashpot model combined with a constant cohesion force (linear model) were used as the contact force model. The simulations were made in rectangular domain with Lees-Edwards boundary condition [2] that applies the simple shear flow condition on the domain. The effect of shear rate on the formation of aggregates was studied.

The results of the linear model show that the relation between the shear rate and the maximum size of aggregates is well described by the dynamic adhesion/cohesion model proposed by Kobayashi et al. [2]. It means that the development of aggregation in granular shear flow can be scaled by the critical collision velocity that characterizes the rebound/sticking behavior of collision between a couple of particles. It is found that the results predicted by the JKR model agree well with those by the linear model.

[1] Johnson, K.L., Kendall, K., Roberts, A.D., Proc. R. Soc. London, A 324 (1971) 301-313.

[2] Lees, A.W., Edwards, S.F., J, Phys. C: Solid State Phys., 5 (1972) 1921-1929.

[3] Kobayashi, T., Tanaka, T., Shimada, N., Kawaguchi, T., Powder Technol., 248, (2013) 143-152.