Numerical simulation of polydisperse granular column collapse on an inclined erodible bed

Abstract

Granular flow is extremely complex owing to the polydispersity of the sliding mass and the erodibility of the underlying bed. However, systematic studies addressing the polydisperse granular flow over an erodible bed remain scarce. Based on a well-validated quasi-three-dimensional Discrete Element Method (quasi-3D DEM), the collapse process of a polydisperse granular column on an inclined erodible bed is investigated in this study. The influences of granular column composition, bed erodibility and slope on the collapse process are analyzed. The results indicate that a stratification phenomenon occurs in the final collapse morphology due to the particle segregation effect. As the proportion of coarse particles in the granular column increases, both the erosion area and runout distance gradually decrease, while the separation degree between different particle phases increases. As bed particle size increases, erosion phenomena become more pronounced while the runout distance gradually diminishes. Moreover, an increase of bed slope results in the particles gaining more kinetic energy, thereby significantly increasing the erosion area and the runout distance. These insights deepen the understanding of granular flow dynamics.