ARRANGEMENT OF DISCS IN 2D BINARY ASSEMBLIES

We study arrangements of the two species of discs in binary assemblies at an intermediate scale, Small discs rearrange along large ones in c lusters whose mass and compactness are analyzed with the tools of perc olation. The assemblies are generated analogically on an air table or numerically from RSA or Powell algorithms. At a given packing fraction , an infinite cluster of small discs exists above a critical compositi on; a phenomenological expression for this threshold is proposed. Like in usual percolation problems, the number of inner links in a cluster is a linear function of its mass, with a slope depending both on the packing fraction, the composition of the mixture and the building proc edure. An approximate expression is derived for it.