Departamento de Física, Facultad de Ciencias, Universidad de Navarra, E-31080 Pamplona, Spain.
Phys Rev E. 2017 May;95(5-1):052904. doi: 10.1103/PhysRevE.95.052904. Epub 2017 May 31.
We experimentally analyze the effect that particle size has on the mass flow rate of a quasi two-dimensional silo discharged by gravity. In a previous work, Janda et al. [Phys. Rev. Lett. 108, 248001 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.248001] introduced a new expression for the mass flow rate based on a detailed experimental analysis of the flow for 1-mm diameter beads. Here, we aim to extend these results by using particles of larger sizes and a variable that was not explicitly included in the proposed expression. We show that the velocity and density profiles at the outlet are self-similar and scale with the outlet size with the same functionalities as in the case of 1-mm particles. Nevertheless, some discrepancies are evidenced in the values of the fitting parameters. In particular, we observe that larger particles lead to higher velocities and lower packing fractions at the orifice. Intriguingly, both magnitudes seem to compensate giving rise to very similar flow rates. In order to shed light on the origin of this behavior we have computed fields of a solid fraction, velocity, and a kinetic-stress like variable in the region above the orifice.
我们通过实验分析了粒径对重力排放准二维筒仓质量流量的影响。在之前的工作中，Janda 等人[Phys. Rev. Lett. 108, 248001 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.248001]基于对 1mm 直径珠子流动的详细实验分析，提出了一个新的质量流量表达式。在这里，我们旨在通过使用更大尺寸的颗粒和未明确包含在提出的表达式中的变量来扩展这些结果。我们表明，出口处的速度和密度分布是自相似的，并与出口尺寸成比例，与 1mm 颗粒的情况具有相同的功能。然而，在拟合参数的值中存在一些差异。特别是，我们观察到较大的颗粒在孔口处导致更高的速度和更低的堆积分数。有趣的是，这两个量级似乎相互补偿，导致非常相似的流量。为了阐明这种行为的起源，我们在孔口上方的区域计算了固相分数、速度和类似动应力的变量的场。
