关键词: 分形结构, 团聚体, 分散混合, 流场形式, 分散效率

Abstract:

In this paper,a 2-D discrete element program Demix2D is developed to investigate the dispersive mixingmechanism and dynamic details of particulate agglomerates by introducing the van der Waals force and the fluiddrag force into the classic discrete element model. Then,the dispersive mixing process of the agglomerates withfractal structure is numerically simulated in three different flow fields,namely,the steady shear flow field,theelongation flow field and the combined shear and elongation flow field. Simulation results show that ( 1) the agglomeratesin the flow fields first exhibit deformation behavior and then disperse in the manners of erosion and rupture;( 2) under the same flow stress,the elongation flow field has the highest dispersion efficiency with the smallestfinal average fragment size,while the shear flow field has the lowest dispersion efficiency with the largest finalaverage fragment size; and ( 3) with the increase of the flow stress in the same flow field,the dispersion efficiencyincreases and the final average fragment size decreases.

Key words: fractal structure, particulate agglomerate, dispersive mixing, flow field type, dispersion efficiency