Multiphase simulations and experiments of subaqueous granular collapse on an inclined plane in densely packed conditions: Effects of particle size and initial concentration

Subaqueous granular collapse on an inclined plane was investigated by considering the effects of particle size and initial concentration in densely packed conditions. This study adopted the multiphase model developed by Lee [J. Fluid Mech. 907 - A31 (2021)], which can capture pore pressure feedback (an important mechanism in subaqueous granular flows). A new set of laboratory experiments were performed to validate the multiphase model with four different particle sizes (from fine sand to very coarse sand). Generally, the multiphase model can reproduce all the experimental collapse processes well. Four particle sizes and four initial concentrations were examined numerically. The simulated results reveal that both the volume of the sliding mass in the early stages (initial sliding volume) and the front speed increase with increasing particle size. In addition, increasing the initial concentration reduces the initial sliding volume and front speed. The simulated results suggest that the front speed can be expressed as a function of the initial sliding volume. A simplified force balance analysis was performed to examine why the particle size and the initial concentration affect the initial sliding volume.

Automated summary

This study investigates the effects of particle size and initial concentration on subaqueous granular collapse on an inclined plane. Experimental and numerical simulation results validate the multiphase model and reveal that particle size and initial concentration significantly affect the initial sliding volume and front speed.