Dense flows of cohesive granular materials

P. Rognon (1) , Jean-Noël Roux (1) , Mohamed Naaim (2) , François Chevoir (1)

1 LMSGC - Laboratoire des matériaux et structures du génie civil
2 UR ETGR (ETNA) - Érosion torrentielle, neige et avalanches

Using molecular dynamic simulations, we investigate the characteristics of dense flows of model cohesive grains. We describe their rheological behavior and its origin at the scale of the grains and of their organization. Homogeneous plane shear flows give access to the constitutive law of cohesive grains which can be expressed by a simple friction law similar to the case of cohesionless grains, but intergranular cohesive forces strongly enhance the resistance to the shear. Then we show the consequence on flows down a slope: a plugged region develops at the free surface where the cohesion intensity is the strongest. Moreover, we measure various indicators of the microstructure within flows which evidence the aggregation of grains due to cohesion and we analyze the properties of the contact network (force distributions and anisotropy). This provides new insights into the interplay between the local contact law, the microstructure and the macroscopic behavior of cohesive grains.

Mots clés: Rheology; Granular Materials; Cohesion; Discrete Numerical Simulations

Domaines: Dynamique des Fluides [physics.flu-dyn]

P. Rognon, Jean-Noël Roux, Mohamed Naaim, François Chevoir. Dense flows of cohesive granular materials. Journal of Fluid Mechanics, 2008, 596, pp.21-47. ⟨10.1017/S0022112007009329⟩. ⟨hal-00280133⟩