Bhateja Ashish
School of Mechanical Sciences, Indian Institute of Technology Goa, Ponda 403401, Goa, India.
Phys Rev E. 2020 Oct;102(4-1):042904. doi: 10.1103/PhysRevE.102.042904.
This study utilizes computations based on a soft-particle discrete element method for investigating the scaling of velocity in the region of orifice influence situated directly above and in proximity to the outlet in a two-dimensional silo. The velocity at the exit scales with the outlet size (D), in striking agreement with the earlier studies. However, the scaling of velocity upstream of the outlet with D as the length scale does not exist. Consequently, we present a scaling with a length parameter h_{e} being the height of an equi-inertial curve, which is defined to be a curve on which the inertial number is constant, thereby consolidating the coexisting different flow regimes in a discharging silo. The velocity corresponding to an equi-inertial curve, when measured relative to the velocity at the outlet, scales very well with h_{e} for low inertial numbers belonging to the dense flow regime. However, such scaling does not hold for high inertial numbers corresponding to the rapid flow regime in the region located closer to the orifice. We tie this scaling breakdown to the velocity fluctuations in light of the similarity between the profiles of scaled relative velocity and the scaled kinetic pressure, suggesting h_{e} to be a promising candidate for unifying the kinematics of granular flow near the outlet in the silo.
本研究采用基于软颗粒离散元方法的计算，以研究二维筒仓中位于出口正上方及附近的孔口影响区域内速度的标度关系。出口处的速度与出口尺寸（D）成比例，这与早期研究结果惊人地一致。然而，以D作为长度尺度时，出口上游速度的标度关系并不存在。因此，我们提出了一种以长度参数(h_{e})作为标度关系，(h_{e})为等惯性曲线的高度，等惯性曲线定义为惯性数恒定的曲线，从而整合了卸料筒仓中共存的不同流动状态。对于属于密相流态的低惯性数情况，相对于出口处速度测量的等惯性曲线对应的速度与(h_{e})标度关系良好。然而，对于靠近孔口区域内对应于快速流态的高惯性数情况，这种标度关系并不成立。鉴于标度化相对速度和标度化动压的分布相似性，我们将这种标度关系的失效与速度波动联系起来，这表明(h_{e})有望统一筒仓出口附近颗粒流的运动学。
