The Combined Effect of the Cohesion and the Finite-size on the Collapse of Wet Granular Columns

The collapse of a finite-size wet granular column is systematically studied and the determinants affecting its dynamics are analyzed based on the established discrete element model and corresponding small-scale experiments. With the aid of parametric analysis, the dimensionless cohesion parameter containing system size and grain-scale Bond number is proposed, and its relevance in characterizing column stability and collapse dynamics is further confirmed. For the collapse of wet granular columns with a fixed aspect ratio, the initial height contained in the cohesion parameter is verified to be a manifestation of finite-size effect, which is present in a wet granular system and coupled with the cohesive effect. Such coupling effect is taken into account in our proposed universal scaling laws that can be applied to uniformly describe the deposit morphology of wet granular columns after collapse.