涡场中黏附性颗粒团聚体粒径分布的预测

Floc Size Distribution in Steady Vortex Field

黏附性颗粒团聚现象在自然界和工业界普遍存在,扰动流场中黏附性颗粒间的碰撞、摩擦和吸附等动力学行为,导致团聚体形态不断演化,准确预测黏附性颗粒团聚体的粒径分布是调控颗粒团聚过程的重要前提。本文通过二维泰勒格林涡场中黏附性颗粒团聚的数值模拟研究,明确了利用Monte Carlo模型预测团聚体粒径分布的可行性及其适用范围,发现当黏附性颗粒间内聚数小于3.5×10^(−4)时,Monte Carlo模型可较好的预测团聚体粒径分布,且相对误差小于±30%;而当内聚数大于3.5×10^(−4)后,Monte Carlo模型不再适用。

We develop a physical and computational method to directly simulate the flocculation of cohesive particles in cellular flow fields by one-way coupling.The cellular flow consists of Taylor-Green vortices and has been proved to be a simple but robust analytical framework for the study of turbulence,it can capture key features of vortical effects on particles.Our numerical method can separately consider the cohesion,lubrication and direct contact forces for each pair of particles,thereby allowing us to conduct a detailed analysis of their influences on the flocculation process in vortices.By comparing with our numerical results,a previous model based on the Monte Carlo Method is recommended to predict the floc size distribution.