Liquid-like granular film from granular jet impact

- The granular film and the diffuse pattern from granular jet impact are identified.
- A new method of changing solid content ratio is used to modulate the flow patterns.
- The solid content ratio is a key factor to the regimes of granular jet impact.
- The circular motion of particles is important for the formation of the granular film.

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 ⩽ 6.5 m/s), the particle diameter (82 ⩽ d ⩽ 350 μm), the jet diameter (1 ⩽ D ⩽ 12 mm), 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.

121