For two simple setups it is discussed, how dissipative grain-grain interactions give rise to unexpected properties on large scales. In the rst example, a spherical particle rolling along a rough surface experiences an eeective viscous friction on large time scales. It is due to temporal correlations among collisions with incomplete normal restitution. The second example is a sheared granular pa...

We describe experiments that probe a number of different types of granular flow where either gravity is effectively eliminated or it is modulated in time. These experiments Include the shaking of granular materials both vertically and horizontally, and the shearing of a 2D granular material. For the shaken system, we identify interesting dynamical phenomena and relate them to standard simple fr...

Most studies on granular physics have focused on dry granular media, with no liquids between the grains. However, in geology and many real world applications (e.g., food processing, pharmaceuticals, ceramics, civil engineering, constructions, and many industrial applications), liquid is present between the grains. This produces inter-grain cohesion and drastically modifies the mechanical proper...

We investigate the quasistatic mechanical response of soils under cyclic loading using a discrete model of randomly generated convex polygons. This response exhibits a sequence of regimes, each one characterized by a linear accumulation of plastic deformation with the number of cycles. At the grain level, a quasiperiodic ratchetlike behavior is observed at the contacts, which excludes the exist...

The dominant mechanism affecting the flow behavior of granular materials is the random motions of particles resulted from the interactive collisions between particles. The velocity fluctuations induce the segregation in granular flows. The different physical properties of granular material were used to investigate the segregation in a vibrated granular bed in this paper. The image processing te...