Pournin L, Ramaioli M, Folly P, Liebling Th M
Mathematics Institute, Ecole Polytechnique Fédérale de Lausanne - EPFL, CH-1015 Lausanne, Switzerland.
Eur Phys J E Soft Matter. 2007 Jun;23(2):229-35. doi: 10.1140/epje/i2007-10176-5.
We study the jamming of bead assemblies placed in a cylindrical container whose bottom is pierced with a circular hole. Their jamming behavior is quantified here by the median jamming diameter, that is the diameter of the hole for which the jamming probability is 0.5. Median jamming diameters of monodisperse assemblies are obtained numerically using the Distinct Element Method and experimentally with steel beads. We obtain good agreement between numerical and experimental results. The influence of friction is then investigated. In particular, the formation of concentric bead rings is observed for low frictions. We identify this phenomenon as a boundary effect and study its influence on jamming. Relying on measures obtained from simulation runs, the median jamming diameter of bidisperse bead assemblies is finally found to depend only on the volume-average diameter of their constituting beads. We formulate this as a tentative law and validate it using bidisperse assemblies of steel beads.
我们研究放置在底部有一个圆形孔的圆柱形容器中的珠子组件的堵塞情况。这里通过中值堵塞直径来量化它们的堵塞行为，中值堵塞直径即堵塞概率为0.5时的孔的直径。使用离散单元法通过数值计算得到单分散组件的中值堵塞直径，并通过实验使用钢珠得到该直径。我们在数值结果和实验结果之间取得了良好的一致性。然后研究了摩擦力的影响。特别地，在低摩擦力情况下观察到了同心珠环的形成。我们将此现象识别为边界效应并研究其对堵塞的影响。基于模拟运行得到的测量结果，最终发现双分散珠子组件的中值堵塞直径仅取决于其组成珠子的体积平均直径。我们将此表述为一个初步定律，并使用钢珠的双分散组件对其进行验证。
