Eur. Phys. J. E (2009) 30: 395-401
https://doi.org/10.1140/epje/i2009-10537-0

Regular Article

Rheology of a sonofluidized granular packing

¹ Centro de Investigación en Materiales Avanzados S.C., Nuevo León, México
² Laboratoire de Physique et Mécanique des Milieux Hétérogènes (UMR 7636 et Universités Paris 6 et Paris 7), 10 rue Vauquelin, 75005, Paris, France

^* e-mail: gabriel.caballero@cimav.edu.mx

Received: 24 June 2009
Revised: 20 October 2009
Accepted: 5 November 2009
Published online: 9 December 2009

Abstract

We report experimental measurements on the rheology of a dry granular material under a weak level of vibration generated by sound injection. First, we measure the drag force exerted on a wire moving in the bulk. We show that when the driving vibration energy is increased, the effective rheology changes drastically: going from a non-linear dynamical friction behavior --weakly increasing with the velocity-- up to a linear force-velocity regime. We present a simple heuristic model to account for the vanishing of the stress dynamical threshold at a finite vibration intensity and the onset of a linear force-velocity behavior. Second, we measure the drag force on spherical intruders when the dragging velocity, the vibration energy, and the diameters are varied. We evidence a so-called “geometrical hardening" effect for smaller-size intruders and a logarithmic hardening effect for the velocity dependence. We show that this last effect is only weakly dependent on the vibration intensity.