Structural signature of binary sphere mixtures under air impact

Abstract

Packings of binary spheres formed under air impact were simulated using the coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach. The effects of particle size ratio (PSR) on structural properties of the packings before and after air impact were analysed. The results showed that the air impact condensed the packings. The second peak in the RDF curves became more apparent and the third peak gradually disappeared in the final packings with increasing PSR. The number of contacts between large spheres decreased, while the contacts between large and small spheres increased under the effect of air impact. The orientation of the contacts tended to be more directional for the final packings. Radical tessellation analyses indicated that for both initial and final packings, two peaks were always formed in the distributions of face number per cell, face area and relative volume, while only one peak appeared in the distributions of edge number and perimeter. Furthermore, the average metrical properties for large particles hardly changed with PSR in the final packings, while those for small or all particles decreased after air impact.