Granular column collapse: Analysing the effects of gravity levels

Abstract

In this study, we investigated the effect of gravity level on the collapse of granular column using the Smoothed Particle Hydrodynamics (SPH) method based on the Mohr-Coulomb model. After validating the model with existing experimental studies, a dimensional analysis of the system’s scaling factors was performed to evaluate the influence of varying gravity levels. The results show that gravity significantly influences collapse dynamics, particularly in shortening the collapse time. To predict collapse time, we propose two models that account for varying gravity acceleration (g), both of which scale positively with n^−1/2 (g = nG, where n is the gravity scaling factor, G = 9.81 m/s²). We find that the non-dimensional collapse time, $t_{\infty }/{\tau }_c$ (where $t_{\infty }$ is the collapse time, and ${\tau }_c=\sqrt{h_0/g}$, with $h_0$ representing the initial height), is influenced by the initial aspect ratio, a (defined as $a=h_0/r_0$, where r₀ is initial radius of the column). While gravity does impact collapse dynamics, its effects on the deposit run-out distance and final height remain consistently scaled at 1.0 across varying gravity levels. Additionally, we propose a modified mobility angle, $\theta \prime$, to investigate the effect of gravity on flow mobility, which aligns with expected gravity scaling. Furthermore, our findings are supported by observations of natural landslides in the Solar System. A multiscale analysis reveals that the spreading range of collapse is contingent on the sample volume and initial potential energy as opposed to gravity. This study has potential applications for investigating the collapse mechanisms of granular materials in planetary exploration.