Designing non-segregating granular mixtures

TL;DR

This paper develops a methodology to design granular mixtures that do not segregate by balancing size and density-driven mechanisms, validated through DEM simulations of heap flow.

Contribution

It introduces a novel approach to create non-segregating mixtures by balancing size and density effects, supported by simulation results.

Findings

Segregation is minimized near the equilibrium condition.

The combined size and density model accurately predicts the transition.

DEM simulations confirm the effectiveness of the design methodology.

Abstract

In bidisperse particle mixtures varying in size or density alone, large particles rise (driven by percolation) and heavy particles sink (driven by buoyancy). When the two particle species differ from each other in both size and density, the two segregation mechanisms either enhance (large/light and small/heavy) or oppose (large/heavy and small/light) each other. In the latter case, an equilibrium condition exists in which the two segregation mechanisms balance and the particles no longer segregate. This leads to a methodology to design non-segregating particle mixtures by specifying particle size ratio, density ratio, and mixture concentration to achieve the equilibrium condition. Using DEM simulations of quasi-2D bounded heap flow, we show that segregation is significantly reduced for particle mixtures near the equilibrium condition. In addition, the rise-sink transition for a range of particle size and density ratios matches the combined size and density segregation model predictions.