Friday, December 14, 2012

1212.3202 (Luis A. García-Trujillo et al.)

Granular Casimir effect and depletion induced phenomena in mixtures of
rods and spheres
   [PDF]

Luis A. García-Trujillo, Gustavo M. Rodríguez-Liñán, Jorge F. Reyes-Tendilla, Yuri Nahmad-Molinari, Gabriel Pérez-Ángel
A novel phenomenon analogous to the quantum and critical Casimir effects is observed in a quasi-2D vertically shaken granular gas of rods and spheres. This granular Casimir attraction increases as the shaking intensity or the rod length is increased. Velocity distributions of spheres inside and outside the Casimir-like configurations are measured, showing a clear suppression of the momentum acquired by the spheres in direction perpendicular to the rods due to inelastic collapse. Excluded volume effects are measured trough liberated volume as a function of time. The apparition of stable Casimir-like configurations instead of compact hexagonal aggregates reveals a stronger attraction than the one purely induced by depletion forces. Furthermore, evidence of layering of spheres close to the boundaries (resembling the ordering of water on a surface) is reported.
View original: http://arxiv.org/abs/1212.3202

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