A MODEL OF BINARY ASSEMBLIES OF DISKS AND ITS APPLICATION TO SEGREGATION STUDY

We propose a theoretical model of random binary assemblies of discs wh ich is the extension at any packing fraction of a model previously des cribed by Dodds for dense packings. In dilute assemblies, the notion o f contact between the grains must be replaced by that of neighbourhood of the grains. We define the neighbours of a disc through the radical tesselation. The model is tested on packings built grain after grain, obtained from numerical simulations. Its results are then compared wi th experimental results obtained on assemblies built on an air table : this shows that the possibility of rearrangement in those assemblies leads to segregation at a local scale.