01838nas a2200169   4500008004100000022001400041245007800055210006900133260007900202300001100281490000700292520120000299100002301499700002101522700002101543856010401564       2009                        eng d  a1539-375500aPhysical test of a particle simulation model in a sheared granular system0 aPhysical test of a particle simulation model in a sheared granul  aONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USAbAMER PHYSICAL SOCcSEP  a0313050 v803 a<p>We report a detailed comparison of a slow gravity-driven sheared granular flow with a discrete-element simulation performed in the same geometry. In the experiments, grains flow inside a silo with a rectangular cross section and are sheared by a rough boundary on one side and smooth boundaries on the other sides. Individual grain position and motion are measured using a particle index-matching imaging technique where a fluorescent dye is added to the interstitial liquid which has the same refractive index as the glass beads. The simulations use a Cundall-Strack contact model between the grains using contact parameters that have been used in many other previous studies and ignore the hydrodynamic effects of the interstitial liquid. Computations are performed to understand the effect of particle coefficient of friction, elasticity, contact model, and polydispersity on mean flow properties. We then perform a detailed comparison of the particle fluctuation properties as measured by the displacement probability distribution function and the mean square displacement. All in all, our study suggests a high level of quantitative agreement between the simulations and experiments.</p>1 aRycroft, Chris, H.1 aOrpe, Ashish, V.1 aKudrolli, Arshad  uhttp://library.ncl.res.in/content/physical-test-particle-simulation-model-sheared-granular-system-002524nas a2200289   4500008004100000020002200041022001400063245005200077210005200129260021600181300001200397490000900409520151800418653000801936653001401944653001301958653001901971653001101990653002302001100002102024700002302045700002502068700002002093700002002113700001602133856008502149       2010                        eng d  a978-0-7354-0772-5  a0094-243X00aShear induced diffusion in dense granular flows0 aShear induced diffusion in dense granular flows  a2 Huntington Quadrangle, STE 1NO1, Melville, NY 11747-4501 USAbIUTAM; ISIMM; Italian Inst Higher Math; US Natl Sci Fdn; Reg Council Reggio Calabria; Prov Reggio Calabria; Mediterranean Univ Reggio CalabriacJUN  a221-2290 v12273 a<p>The dynamics of dense granular flows subjected to gravity induced shear are investigated experimentally using the refractive index matching technique. The system consists of grains flowing inside a bin with a rectangular cross-section and sheared by a rough boundary on one side and smooth boundaries on the remaining sides. The particles flow within a viscous interstitial liquid having the same refractive index as particles and are imaged in the bulk using laser fluorescence. The particle positions are identified very accurately and tracked over long durations to obtain the mean and fluctuating properties. The shear is observed to be non-linear and localized in a region of 3 to 4 particles near the boundary. The boundary imposes a packing order, and the grains are observed to flow in layers, parallel to the shearing boundary, which get progressively more disordered with distance from the walls. We have also carried out soft particle simulations in a equivalent system incorporating the Cundall-Strack contact model between the particles and ignoring the hydrodynamic effects of the interstitial liquid to understand the effect of particle friction coefficient, elasticity, contact model and polydispersity on the mean and fluctuating flow properties. We find the mean velocity and the number density of the particles as a function of flow cross-section and the particle fluctuation properties observed in the experiments and the simulations to in very good agreement after appropriate scaling.</p>10aDEM10aDiffusion10agranular10aindex matching10aLAMMPS10alaser fluorescence1 aOrpe, Ashish, V.1 aRycroft, Chris, H.1 aKudrolli, Arshad, A.1 aGoddard, J., D.1 aJenkins, J., T.1 aGiovine, P.  uhttp://library.ncl.res.in/content/shear-induced-diffusion-dense-granular-flows-0