Sat, 05 Jul 2008 21:49:54 BST CiteULike: kdesmond's Crassous http://www.citeulike.org/user/kdesmond/author/Crassous CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/kdesmond/article/2747227 <i>Granular Matter, Vol. 7, No. 4. (11 November 2005), pp. 185-190.</i><br /><br />We describe a dynamic light scattering experiment designed in order to study creep motion in granular materials. This method is based on the recording of the speckle pattern with a charge coupled device (CCD) camera. The autocorrelation function of the scattered electric field is calculated and related to the displacement field of the beads. As an application, the measurement of the thermal expansion of a granular material subjected to temperature variations is presented. Probing creep motion in granular materials with light scattering Linda Djaoui Jérôme Crassous doi:10.1007/s10035-005-0210-5 Granular Matter, Vol. 7, No. 4. (11 November 2005), pp. 185-190. 2008-05-02T23:12:19-00:00 2005 Granular Matter 7 4 185 190 granular_flow qualifier http://www.citeulike.org/user/kdesmond/article/2294318 <i>Nature, Vol. 396, No. 6713. (1998), pp. 735-737.</i><br /><br />In 1773 Coulomb recognized that the static properties of granular systems can be discussed in terms of the frictional properties between different layers, leading to his relationship between the angle of repose of a granular pile (0) and the coefficient of static friction s: tan 0 =s. Two centuries later, solid friction and granular media still present many puzzles. One such is that the coefficient of static friction depends on the time during which the solids remain in contact before the measurement. Here we show that this ageing effect is manifested too in the angle of repose of granular media and originates from capillary condensation of water vapour between the packed particles, leading to the formation of water bridges. By assuming that the kinetics of this process are governed by the thermally activated nucleation of bridges, we can reproduce both the time- and humidity-dependence of the ageing behaviour. Our results also clarify the kinetics of adsorption in porous media more generally. Moisture-induced ageing in granular media and the kinetics of capillary condensation L Bocquet E Charlaix S Ciliberto J Crassous Nature, Vol. 396, No. 6713. (1998), pp. 735-737. 2008-01-27T03:46:20-00:00 1998 Nature 396 6713 735 737 granular_wet qualifier