黏附性颗粒团聚体在剪切流场中分散行为的数值模拟

Numerical Simulation of Dispersion of Adhesive Particulate Agglomerates in the Shear Flow Field

为深入了解黏附性颗粒团聚体在剪切流场中的形态演变和分散机理,建立了黏附性颗粒离散元模型:基于JKR理论计算接触颗粒间的法向力,基于Thornton理论计算接触颗粒间的切向力,并考虑滚动摩擦力矩、非接触颗粒间的范德华力和流体拖曳力对颗粒运动的影响。使用自主开发的颗粒凝聚和分散模拟软件DEMix3D,模拟了黏附性颗粒团聚体在剪切流场作用下的分散过程。结果表明,在剪切流场中,黏附性颗粒团聚体会发生破裂和重组行为;颗粒表面能大的团聚体分散速度更快;颗粒表面能小的团聚体分散完成后碎片加权颗粒平均数更小,分散效果更好。

In this paper,a discrete element model of adhesive particles was established to investigate the morphological evolution and dispersion mechanism of adhesive particulate agglomerates in the shear flow field.In this model,the normal force between contact particles was calculated based on JKR theory,the tangential force between contact particles was calculated based on Thornton theory,and considered the effects of rolling friction torque,van der Waals force between non-contact particles and fluid drag on particle motion.The software DEMix3D which could simulate the process of aggregation and dispersion of fractal aggregates was developed to simulate the dispersion of adhesive particulate agglomerates in the shear flow field.The results show that during the process of dispersing,the adhesive particulate agglomerates are fractured and reunited and the agglomerates with larger surface energy will disperse faster.As the decrease of surface energy,the final average fragment size could decrease and the dispersion degree could be better.