Valdez Miguel A, Gámez-Corrales Rogelio
Departamento de Física and Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, Rosales y Transversal, 83000 Hermosillo, Sonora, Mexico.
J Colloid Interface Sci. 2003 Nov 1;267(1):233-42. doi: 10.1016/s0021-9797(03)00677-5.
In this work we performed nonequilibrium Brownian dynamics (NEBD) computer simulations of highly charged colloidal particles in diluted suspension under a parabolic flow in cylindrical pores. The influence of charged and neutral cylindrical pores on the structure and rheology of suspensions is analyzed. A shear-induced disorder-order-disorder-like transition was monitored for low shear rates and small pore diameters. We calculate the concentration profiles, axial distribution functions, and axial-angular pair correlation functions to determine the structural properties at steady state for a constant shear flow for different pore sizes and flow strengths. Similar behavior has been observed in a planar narrow channel in the case of charged interacting colloidal particles (M.A. Valdez, O. Manero, J. Colloid Interface Sci. 190 (1997) 81). The mobility of the particles in the radial direction decreases rapidly with the flow and becomes practically frozen. The flow exhibits non-Newtonian shear thinning behavior due to interparticle interactions and particle-wall interaction; the apparent viscosity is lower as the pore diameter decreases, giving rise to an apparent slip in the colloidal suspension. The calculated slip velocity was higher than that obtained in a rectangular slit under shear flow.
在这项工作中，我们对圆柱孔中抛物线流作用下稀释悬浮液中高电荷胶体颗粒进行了非平衡布朗动力学（NEBD）计算机模拟。分析了带电和中性圆柱孔对悬浮液结构和流变学的影响。在低剪切速率和小孔径情况下监测到了类似剪切诱导的无序 - 有序 - 无序转变。我们计算了浓度分布、轴向分布函数和轴向 - 角向对关联函数，以确定不同孔径和流动强度下恒定剪切流稳态时的结构性质。在带电相互作用胶体颗粒的情况下，在平面窄通道中也观察到了类似行为（M.A. 瓦尔迪兹、O. 马内罗，《胶体与界面科学杂志》190 (1997) 81）。颗粒在径向方向上的迁移率随流动迅速降低并几乎冻结。由于颗粒间相互作用和颗粒 - 壁相互作用，流动呈现非牛顿剪切变稀行为；随着孔径减小，表观粘度降低，导致胶体悬浮液中出现表观滑移。计算得到的滑移速度高于剪切流下矩形狭缝中的滑移速度。
