Splash Detail Due to Grain Incident on Granular Bed

TL;DR

This study uses DEM simulations to analyze how grain impact causes splashes on different granular beds, revealing the influence of packing structure on ejection angles and speeds, with results aligning with prior experiments and novel insights into structured beds.

Contribution

It demonstrates the significant effect of granular bed structure on splash dynamics and provides new simulation data for FCC-structured beds not previously experimentally confirmed.

Findings

Mean ejection angle matches previous experiments for random beds.

FCC beds produce larger ejection angles, a novel simulation result.

Ejection speed distributions evolve from power-law to lognormal over time.

Abstract

Using the discrete element method (DEM), we study the splash processes induced by the impact of a grain on two types of granular beds, namely, randomly packed and FCC-structured beds.Good correspondence is obtained between our numerical results and the findings of previous experiments, and it is demonstrated that the packing structure of the granular bed strongly affects the splash process.The mean ejection angle for the randomly packed bed is consistent with previous experimental results. The FCC-structured bed yields a larger mean ejection angle; however, the latter result has not been confirmed experimentally. Furthermore, the ejection angle distributions and the vertical ejection speeds for individual grains vary depending on the relative timing at which the grains are ejected after the initial impact. Obvious differences are observed between the distributions of grains ejected during the earlier and later splash periods: the form of the vertical ejection speed distribution varies from a power-law form to a lognormal form with time, and more than 80\% of the kinetic energy of all ejected grains is used for earlier ejected grains.