Experimental and numerical investigation on the packing of binary mixtures of spheres and ellipsoids

The packing of binary mixtures of spheres and ellipsoids are investigated by both physical experiments and discrete element method (DEM) in this work. The DEM model is first validated through comparison with experimental results in terms of packing density. The equivalent packing diameter is confirmed to be much better than the equivalent volume diameter in the characterization of particle size of ellipsoids. Then some key variables, including size ratio and their volume fractions and particle shape, are chosen to study their effects on the coordination number of binary mixtures of spheres and ellipsoids. The results show that increasing the size or volume fraction of one component in the mixture will increase the contacts of this component with the particles around this component. At fixed solid volume fraction, an ellipsoidal particle has more contacts with the departure of particle shape from a perfect sphere.