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Investigating how tightly objects pack space is a long standing problem, with relevance for many disciplines ranging from discrete mathematics and the theory of glasses to the shipping industry.
Here we report on the fundamental yet so far overlooked geometric property that disordered mono-disperse spherical bead packs have significant local structural anisotropy manifest in the shape of the free space associated with each bead.
Jammed disordered packings from several types of experiments and simulations reveal very similar values of the cell anisotropy, showing a linear decrease with packing fraction.
Strong deviations from this trend are observed for unjammed configurations and for partially-crystalline packings above 64%.
These findings suggest an inherent geometrical reason why, in disordered packings, anisotropic shapes can fill space more efficiently than spheres and have implications for packing effects in non-spherical liquid crystals, granular aggregates, foams and structural glasses.
Ref. Gerd E. Schröder-Turk, Walter Mickel , Matthias Schröter, Gary W. Delaney, Mohammad Saadatfar, Tim J. Senden, Klaus Mecke and Tomaso Aste, Disordered Spherical Bead Packs are Anisotropic, to be submitted( 2010) |
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