Packing and flow profiles of soft grains in 3D silos reconstructed with X-ray computed tomography

The outflow of hard grains from storage containers with narrow outlets has been extensively studied in the past. Most experiments focused on discharge rates and avalanche statistics. Flow fields inside such containers have been detected optically in two-dimensional (2D) or quasi-2D geometries. Soft grains behave qualitatively different in many respects, both in their static packing properties and during silo discharge. We employ X-ray computed tomography to map the particles in a 3D container and we compare the static packing characteristics and the flow profiles of soft hydrogel spheres with those of hard spheres. The local fill fraction of the soft grains depends upon the depth below the granular surface. The outflow of the soft, low frictional hydrogel spheres involves the complete container volume, stagnant zones are absent.

[1]  E. Weeks,et al.  Clogging of soft particles in two-dimensional hoppers. , 2015, Physical review. E.

[2]  Flow-rate fluctuations in the outpouring of grains from a two-dimensional silo. , 2009, Physical review. E, Statistical, nonlinear, and soft matter physics.

[3]  J. van de Velde,et al.  The flow of granular solids through orifices , 1961 .

[4]  Angel Garcimartín,et al.  Jamming during the discharge of grains from a silo described as a percolating transition. , 2003, Physical review. E, Statistical, nonlinear, and soft matter physics.

[5]  D. C. Rapaport,et al.  Granular flow from a silo: Discrete-particle simulations in three dimensions , 2001 .

[6]  Iker Zuriguel,et al.  Clogging of granular materials in silos: effect of gravity and outlet size. , 2016, Soft matter.

[7]  E. Weeks,et al.  Clogging of soft particles in 2D hoppers , 2017 .

[8]  Thomas M Truskett,et al.  Is random close packing of spheres well defined? , 2000, Physical review letters.

[9]  R P Behringer,et al.  How granular materials jam in a hopper. , 2011, Chaos.

[10]  Charles S. Campbell,et al.  Granular material flows – An overview , 2006 .

[11]  Ralf Stannarius,et al.  Flow of anisometric particles in a quasi-two-dimensional hopper. , 2018, Physical review. E.

[12]  Andreas Schadschneider,et al.  Critical bottleneck size for jamless particle flows in two dimensions. , 2014, Physical review letters.

[13]  Angel Garcimartín,et al.  Jamming during the discharge of granular matter from a silo. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[14]  T. Majmudar,et al.  Contact force measurements and stress-induced anisotropy in granular materials , 2005, Nature.

[15]  Krzysztof Grudzień,et al.  Quantitative estimation of volume changes of granular materials during silo flow using X-ray tomography , 2011 .

[16]  D. Maza,et al.  Jamming and critical outlet size in the discharge of a two-dimensional silo , 2008 .

[17]  Jin Y. Ooi,et al.  A numerical study of wall pressure and granular flow in a flat-bottomed silo , 2015 .

[18]  F. Radjai,et al.  Modeling Granular Materials: Century-Long Research across Scales , 2017 .

[19]  Iker Zuriguel,et al.  Invited review: Clogging of granular materials in bottlenecks , 2014, 1412.5806.

[20]  J. R. Darias,et al.  Silo collapse under granular discharge. , 2012, Physical review letters.

[21]  S. Wegner,et al.  Outflow and clogging of shape-anisotropic grains in hoppers with small apertures. , 2017, Soft matter.

[22]  Andrew Drescher,et al.  Arching in hoppers: II. Arching theories and critical outlet size , 1995 .

[23]  É. Clément,et al.  Unjamming a granular hopper by vibration , 2009, 0907.0114.

[24]  Nicolas Brodu,et al.  Refractive index matched scanning and detection of soft particles. , 2017, The Review of scientific instruments.

[25]  Nicolas Brodu,et al.  Spanning the scales of granular materials through microscopic force imaging , 2015, Nature communications.

[26]  H. Jaeger,et al.  Granular solids, liquids, and gases , 1996 .

[27]  J. A. Fox,et al.  Experimental Investigation of the Stability of Hagen‐Poiseuille Flow , 1968 .

[28]  F. C. Franklin,et al.  Flow of granular material through a circular orifice , 1955 .

[29]  P. Gennes.  Granular Matter: A Tentative View , 1999 .

[30]  Angel Garcimartín,et al.  Role of vibrations in the jamming and unjamming of grains discharging from a silo. , 2009, Physical review. E, Statistical, nonlinear, and soft matter physics.

[31]  D. Durian,et al.  The sands of time run faster near the end , 2016, Nature Communications.

[32]  Hu Zheng,et al.  Imaging soft sphere packings in a novel triaxial shear setup , 2013 .

[33]  Guy T. Houlsby,et al.  The flow of granular materials—I: Discharge rates from hoppers , 1982 .

[34]  I Zuriguel,et al.  Stability of clogging arches in a silo submitted to vertical vibrations. , 2015, Physical review. E, Statistical, nonlinear, and soft matter physics.

[35]  Christian Veje,et al.  Stress Fluctuations in a 2D Granular Couette Experiment: A Continuous Transition , 1999 .

[36]  Angel Garcimartín,et al.  Flow and clogging in a silo with an obstacle above the orifice. , 2012, Physical review. E, Statistical, nonlinear, and soft matter physics.

[37]  D. Durian,et al.  Granular discharge rate for submerged hoppers , 2013, 1307.2812.

[38]  Junyao Tang,et al.  Orientation, flow, and clogging in a two-dimensional hopper: Ellipses vs. disks , 2015, 1510.07940.

[39]  I. Zuriguel,et al.  Force analysis of clogging arches in a silo , 2013 .

[40]  N. Otsu.  A threshold selection method from gray level histograms , 1979 .

[41]  J. Steele,et al.  FLOW RATES OF GRAIN THROUGH VARIOUS SHAPES OF VERTICAL AND HORIZONTAL ORIHCES , 1991 .

[42]  Pak,et al.  Jamming of Granular Flow in a Two-Dimensional Hopper. , 2001, Physical review letters.

[43]  A. Vidales,et al.  The effect of the packing fraction on the jamming of granular flow through small apertures , 2011, 1110.4790.

[44]  Georg Rose,et al.  Packing, alignment and flow of shape-anisotropic grains in a 3D silo experiment , 2016, 1609.02752.

[45]  D. J. Durian,et al.  Granular discharge and clogging for tilted hoppers , 2008, 0810.0495.

[46]  Angel Garcimartín,et al.  Silo clogging reduction by the presence of an obstacle. , 2011, Physical review letters.

[47]  Rui Xiao,et al.  Discrete element method modeling of non-spherical granular flow in rectangular hopper , 2010 .

[48]  I Zuriguel,et al.  Flow and clogging of a sheep herd passing through a bottleneck. , 2015, Physical review. E, Statistical, nonlinear, and soft matter physics.

[49]  J. Peixinho,et al.  Dynamics of swelling and drying in a spherical gel , 2015, 1605.00599.

[50]  D J Durian,et al.  Fraction of clogging configurations sampled by granular hopper flow. , 2014, Physical review letters.

[51]  P. Cleary,et al.  Granular flow during hopper discharge. , 2011, Physical review. E, Statistical, nonlinear, and soft matter physics.

[52]  D. Maza,et al.  The flow rate of granular materials through an orifice , 2007, 0707.4550.

[53]  D. Maza,et al.  Disentangling the Free-Fall Arch Paradox in Silo Discharge. , 2015, Physical review letters.

[54]  Jonathan D. Bray,et al.  Influence of Particle Shape and Surface Friction Variability on Response of Rod-Shaped Particulate Media , 2002 .

[55]  Angel Garcimartín,et al.  Breaking arches with vibrations: the role of defects. , 2012, Physical review letters.

[56]  Matthias Schröter,et al.  Analyzing X-ray tomographies of granular packings. , 2016, The Review of scientific instruments.

[57]  K. To.  Jamming transition in two-dimensional hoppers and silos. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[58]  Ignacio Pagonabarraga,et al.  Clogging transition of many-particle systems flowing through bottlenecks , 2014, Scientific Reports.

[59]  J. Loon,et al.  Influence of the gravity on the discharge of a silo , 2013 .

[60]  Rodolfo Omar Uñac,et al.  Experimental study of discharge rate fluctuations in a silo with different hopper geometries , 2012 .

[61]  D. Durian,et al.  Geometry dependence of the clogging transition in tilted hoppers. , 2011, Physical review. E, Statistical, nonlinear, and soft matter physics.

[62]  D. Maza,et al.  Fluctuations of grains inside a discharging two-dimensional silo. , 2011, Physical review. E, Statistical, nonlinear, and soft matter physics.

[63]  K. To,et al.  Granular flow from silos with rotating orifice. , 2019, Physical review. E.

[64]  Carl Wassgren,et al.  Effects of vertical vibration on hopper flows of granular material , 2002 .

[65]  T. Mullin,et al.  Granular segregation driven by particle interactions. , 2015, Physical review letters.

[66]  B. Dalloz-Dubrujeaud,et al.  Discharge flow of a bidisperse granular media from a silo. , 2014, Physical review. E, Statistical, nonlinear, and soft matter physics.

[67]  Istvan Oldal,et al.  Outflow properties of silos: The effect of arching , 2012 .

[68]  Georg Rose,et al.  Effects of grain shape on packing and dilatancy of sheared granular materials. , 2014, Soft matter.

[69]  Heinrich M. Jaeger,et al.  Density fluctuations in vibrated granular materials , 1998 .

[70]  Angel Garcimartín,et al.  Role of driving force on the clogging of inert particles in a bottleneck. , 2014, Physical review. E, Statistical, nonlinear, and soft matter physics.

[71]  Carl Wassgren,et al.  Effects of Horizontal Vibration on Hopper Flows of Granular Materials , 1997 .

[72]  R. Stannarius,et al.  Silo outflow of soft frictionless spheres , 2017, 1708.06824.

[73]  Summer N. Saraf,et al.  Power-law flow statistics in anisometric (wedge) hoppers. , 2011, Physical review. E, Statistical, nonlinear, and soft matter physics.

[74]  Ralf Stannarius,et al.  Magnetic resonance imaging of granular materials. , 2017, The Review of scientific instruments.

[75]  M. A. Aguirre,et al.  Granular flow through an aperture: influence of the packing fraction. , 2014, Physical review. E, Statistical, nonlinear, and soft matter physics.

[76]  Wenqi Zhong,et al.  Flow Behaviors of Non-spherical Granules in Rectangular Hopper , 2010 .

[77]  Angel Garcimartín,et al.  Shape of jamming arches in two-dimensional deposits of granular materials. , 2010, Physical review. E, Statistical, nonlinear, and soft matter physics.