Dynamics of wet granular flows down an inclined plane

Despite the important role of wet granular flows in numerous industrial and natural processes, their rheology in the inertial regime has only recently been formalized [T. T. Vo et al., Nat. Commun. 11, 1476 (2020)] through a single dimensionless number that combines cohesive, confining, and inertial stresses. In this paper, we investigate the applicability of this model to wet granular flows down an inclined plane, specifically analyzing the velocity profiles and their dependence on the slope angle and surface tension of the binding liquid. Using particle dynamics simulations of spherical particles bound by a small volume of wetting liquid in the pendular state, we quantitatively compare model predictions with simulated datasets. The liquid’s influence is represented by a reversible, hysteretic capillary force law. For a range of the slope angle and surface tension values, our results show that the model can be calibrated to predict particle velocity profiles and the thickness of the stable plug that forms at the free surface in a steady flow state. We also explore the role of microstructure and the origins of the model parameters.