Liquid-like granular film from granular jet impact

Abstract

Dynamic behaviors of dense granular jets impacting a flat target are experimentally studied and numerically simulated using the Discrete Element Method. Effects of the granular jet velocity (u0⩽6.5m/s), the particle diameter (82⩽d⩽350μm), the jet diameter (1⩽D⩽12mm), and the volumetric solid content ratio of the granular jet (0.05⩽xp<0.62) on the flow patterns are investigated. Two patterns were identified: the thin, liquid-like granular film and the diffuse pattern. The profile and thickness of granular films have been characterized. The transition critical parameters and maps of the two patterns are obtained in this work. Results show that the regimes of the granular jet impact are primarily determined by the ratio of jet diameter to particle diameter (D/d) and solid content ratio (xp). A compacted dead zone over the target forms with large D/d and xp, which subsequently causes rapid interparticle inelastic collisions and circular motion of the granular film.