Voidage correction method for DEM study of 3D pebble flows in a bed of cycloidal base

Voidage (porosity or void fraction) in packed particles (or pebbles) is of fundamental importance in calculating the pressure drop, obtaining the drag, predicting the bed permeability, estimating the neutron streaming, etc. For the case when particles are deformed, a method of voidage correction during the packing state is proposed using a Discrete Element Method (DEM) simulation of 3D pebble flow inside a bed of cycloidal base. A function to evaluate the remaining volume of a pebble intercepted by horizontal and vertical planes is proposed for voidage calculation. After that, the process of solving voidage distribution is provided in detail. Using this method, the voidage inside the cycloidal-base pebble bed is obtained to refer to reported similar data for validation. This method can be potentially used for dynamical voidage calculation in CFD-DEM simulation which can get suitable voidage distribution after the correction.

填充颗粒（或球团）中的空隙率（Voidage，亦称孔隙度或空隙分数）对于计算压降、获取阻力、预测床层渗透率、估算中子流等具有根本重要性。针对颗粒发生变形的情况，本文提出一种基于摆线基底床内三维球团流动的离散元法（Discrete Element Method, DEM）模拟的填充状态空隙率校正方法。为计算空隙率，本文提出一种用于评估被水平和垂直平面截取的球团剩余体积的函数。随后，本文详细阐述了求解空隙率分布的过程。采用该方法，可得到摆线基底球团床内的空隙率，并与已报道的相似数据进行对比验证。该方法有望应用于CFD-DEM模拟中的动态空隙率计算，经校正后可获得合理的空隙率分布。