刚性散粒体随机堆积的三维数值模拟

3-D Numerical Simulation of Random Packing of Rigid Particulates

在边长（α）分别为球半径（r）15、20和25倍的刚性立方体盒内，随机生成单一球体堆积模型的基础上，利用三维离散单元法（DEM）动态模拟堆积体自重作用下的堆积过程。追踪了颗粒的堆积运动轨迹，并分析了堆积密实度和配位数及其分布规律。结果表明：重力作用下，密实度增加，结构趋于均匀、致密；DEM模拟前、后密实度均随r／α值减小而增加，即边界影响越小散粒体堆积密实度越大；几种情形下的平均配位数均在6．05～6．15之间，接近理论值6。

With the help of a random number generator, mixtures of mono-sized spherical particles were located without overlapping inside rigid cubic hoxes whose edge lengths （α） are 15, 20 and 25 times the radii （r） of the spheres respectively. Discrete element method （DEM） was used to simulate dynamical packing of the particulates in gravity field, Movement of the packing particle can also be traced during the simulation. Structural properties, such as packing density, coordination number and the distribution of coordination number were analyzed. The results indicate that the density increases and the structure of the array becomes denser and more homogenous under the gravitation. Besides, densities before/after DEM simulation tend to increase when r/α decreases.That is to say, the less the wall affects, the denser the array becomes.When extrapolated to zero wall effect, the initial and final packing densities are 0.552 4 and 0.581 7 respectively.The mean coordination number alters in the range of 6.05 - 6.15 under different conditions, which is close to the theoretical value.