Vainshtein P, Shapiro M
Laboratory of Transport Processes in Porous Materials, Faculty of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
J Colloid Interface Sci. 2005 Apr 15;284(2):501-9. doi: 10.1016/j.jcis.2004.08.155.
Hydrodynamic drag and mobility of fractal aggregates in the slip creeping flow regime are calculated. A theoretical continuum model of the gas slip flow past and within agglomerates is developed. It accounts for effects of flow rarefaction and porous fractal structure upon the molecular mean free path, apparent viscosity, and effective permeability of agglomerates. It is shown that flow rarefaction significantly diminishes the aggregates' drag to an extent that cannot be predicted by the Cunningham's drag correction factor. The developed model allows calculation the agglomerates' transport properties in a wide range of fractal dimensions. For low D(f) agglomerates the drag force agrees with the Friedlander's expression based on the Epstein's single sphere drag in the free molecular regime.
计算了分形聚集体在滑移蠕动流态下的流体动力学阻力和迁移率。建立了气体在团聚体外部和内部滑移流动的理论连续介质模型。该模型考虑了流动稀薄化和多孔分形结构对团聚体分子平均自由程、表观粘度和有效渗透率的影响。结果表明，流动稀薄化显著降低了聚集体的阻力，其降低程度无法用坎宁安阻力修正因子预测。所建立的模型能够计算在广泛分形维数范围内团聚体的输运性质。对于低分形维数的团聚体，阻力与基于自由分子流态下爱泼斯坦单球阻力的弗里德兰德表达式一致。
