Dynamic simulation of the centripetal packing of mono-sized spheres

This paper presents a study of the centripetal packing of mono-sized spherical particles simulated by means of the granular dynamic or discrete element method. A packing is formed by imposing an assumed centripetal force on particles randomly generated in a spherical space. Different from the conventional simulation techniques, dynamic information of individual particles including transient forces and trajectory is traced in the present simulation. Structural properties, such as packing density, radial distribution function, coordination number distribution and homogeneity, are analyzed, with particular reference to the eects of the magnitude of the centripetal force and the number of particles. Comparison with the literature results suggests that such a dynamic model can satisfactorily simulate the dynamics of forming a packing and produce more realistic structural information. In particular, it is conrmed that a centripetal packing is not homogeneous in structure, becoming looser as its size or the number of particles increases. The packing has a limit packing density of 0.637{0.645, an overall mean coordination number of around 6.0 and a radial distribution function of clear split second peak. The centripetal force aects the rate of densication and the mean coordination number but not packing density and radial distribution function. c 1999 Elsevier Science B.V. All rights reserved.

[1]  G. D. Scott,et al.  Radial Distribution of the Random Close Packing of Equal Spheres , 1962, Nature.

[2]  P. A. Langston,et al.  Distinct element simulation of interstitial air effects in axially symmetric granular flows in hoppers , 1996 .

[3]  Paul Zulli,et al.  Coordination number of binary mixtures of spheres , 1998 .

[4]  Jodrey,et al.  Computer simulation of close random packing of equal spheres. , 1985, Physical review. A, General physics.

[5]  E. M. Tory,et al.  Simulated random packing of equal spheres , 1973 .

[6]  D. J. Adams,et al.  Computation of Dense Random Packings of Hard Spheres , 1972 .

[7]  E. Liniger,et al.  Packing and Sintering of Two‐Dimensional Structures Made fro Bimodal Particle Size Distributions , 1987 .

[8]  Alex Hansen,et al.  Disorder and granular media , 1993 .

[9]  Anand Jagota,et al.  Micromechanical modeling of powder compacts—I. Unit problems for sintering and traction induced deformation , 1988 .

[10]  E. M. Tory,et al.  Anisotropy in Simulated Random Packing of Equal Spheres , 1968, Nature.

[11]  Wiley,et al.  Numerical simulation of the dense random packing of a binary mixture of hard spheres: Amorphous metals. , 1987, Physical review. B, Condensed matter.

[12]  S. Bryant,et al.  Quantification of Spatial Correlation in Porous Media and Its Effect on Mercury Porosimetry. , 1996, Journal of colloid and interface science.

[13]  Random sequential adsorption of spheres of different sizes , 1992 .

[14]  Randall M. German,et al.  Particle packing characteristics , 1989 .

[15]  E. M. Tory,et al.  Computer simulation of isotropic, homogeneous, dense random packing of equal spheres , 1981 .

[16]  P. Cundall,et al.  A discrete numerical model for granular assemblies , 1979 .

[17]  M. J. Powell.  Computer-simulated random packing of spheres , 1980 .

[18]  Colin Thornton,et al.  Numerical simulation of the impact fracture and fragmentation of agglomerates , 1996 .

[19]  K. Z. Y. Yen,et al.  A dynamic simulation of particle rearrangement in powder packings with realistic interactions , 1992 .

[20]  Aibing Yu,et al.  Numerical simulation of the gas-solid flow in a fluidized bed by combining discrete particle method with computational fluid dynamics , 1997 .

[21]  J. Finney,et al.  Modelling the structures of amorphous metals and alloys , 1977, Nature.

[22]  P. L. Spedding,et al.  SIMULATION OF PACKING DENSITY AND LIQUID FLOW IN FIXED BEDS , 1995 .

[23]  D. Caprion,et al.  Computer investigation of long-range correlations and local order in random packings of spheres. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[24]  Y. Tsuji,et al.  Discrete particle simulation of two-dimensional fluidized bed , 1993 .

[25]  James G. Berryman,et al.  Random close packing of hard spheres and disks , 1983 .

[26]  H. Scott Fogler,et al.  Modeling flow in disordered packed beds from pore‐scale fluid mechanics , 1997 .

[27]  J. D. Bernal,et al.  Random close-packed hard-sphere model. I. Effect of introducing holes , 1967 .

[28]  W. Visscher,et al.  Random Packing of Equal and Unequal Spheres in Two and Three Dimensions , 1972, Nature.

[29]  G. T. Nolan,et al.  Computer simulation of random packing of hard spheres , 1992 .

[30]  Mehta,et al.  Vibrated powders: Structure, correlations, and dynamics. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[31]  J. L. Finney,et al.  Fine structure in randomly packed, dense clusters of hard spheres , 1976 .