A question of scaling in immersed granular collapses

Abstract

Immersed granular collapse is a common benchmark case for numerical modeling of fluid-particle interactions and large deformation of fluid-particle mixtures. Here we study the effects of column size in immersed granular collapses with laboratory experiments and numerical simulations. With controlled initial aspect ratio, packing density, and the same particles (glass beads) and fluid (water), the increase of column size leads to distinct collapse characteristics of longer normalized runout distance and a “granular jump” behind the surge front. Companion CFD-DEM simulations show an unscaled fluid inertia effect as the column size increases, which may underlie the observed column size effect. It suggests that the dynamics of immersed granular collapse is heavily dependent on the scale of the problem if the fluid inertia plays a sufficient role.