Enhancing the linear flow of fine granules through the addition of elongated particles

Abstract

Sandglasses have been used to record time for thousands of years because of their constant flow rates; however, they now are drawing attention for their substantial scientific importance and extensive industrial applications. The presence of elongated particles in a binary granular system is believed to result in undesired flow because their shape implies a larger resistance to flow. However, our experiments demonstrate that the addition of elongated particles can substantially reduce the flow fluctuation of fine granules and produce a stable linear flow similar to that in an hourglass. On the basis of experimental data and previous reports of flow dynamics, we observed that the linear flow is driven by the “needle particle effect,” including flow orientation, reduced agglomeration, and local perturbation. This phenomenon is observed in several binary granular systems, including fine granules and secondary elongated particles, which demonstrates that our simple method can be widely applied to the accurate measurement of granular flows in industry.

Granular particle-shape heterogeneous mixtures discharging through a silo

“…The critical angle of repose of a sandpile consisting of spherical monomer grains was found (Ertaş et al 2002) to increase with the addition of dimers (two spherical particles fused adjacent to each other). However, Guo et al (2015) has observed the 'needle particle effect', where the addition of elongated particles has enhanced the flow of fine granules. They argued that elongated particles played a major role in reducing cohesion and adhesion among fine granules, thus improving the flow conditions.…”

“…However, Guo et al. (2015) has observed the ‘needle particle effect’, where the addition of elongated particles has enhanced the flow of fine granules. They argued that elongated particles played a major role in reducing cohesion and adhesion among fine granules, thus improving the flow conditions.…”

Periodic instationarities of granular flows in conical hoppers

“…the amount of matter passing through the hopper outlet in a certain amount of time. Contemporary studies use the hopper flow configuration to investigate such complex topics as avalanching [23], self-structuration of the granular fabric triggered by the converging flow [24], shape-induced flow regimes [25], or phase change (i.e. jamming) of the granular sample [26].…”