Effect of repulsive interactions on structure and rheology of sheared colloidal dispersions
Effect of repulsive interactions on structure and rheology of sheared colloidal dispersions
复制标题
排斥相互作用对剪切胶体分散体结构和流变学的影响
DOI：
10.1039/c2sm07187h
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发表时间：
2012
期刊：
影响因子：
3.4
通讯作者：
J. Morris
中科院分区：
文献类型：
--
作者：
E. Nazockdast;J. Morris
将Smoluchowski理论推广到具有软排斥作用的胶体悬浮液的结构和流变性研究。进行加速的斯托克斯动力学模拟是为了提供洞察力，并使之能够与理论预测进行直接比较。考虑不同陡度的斥力相互作用，在理论和模拟中使用相同的势，对于以0.1≤Pe≤100表示的不同剪切率，研究了扩展范围排斥作用的影响，其中Pe=6πηA3/kBt是流体动力与布朗力的比率，η是流体粘度，是剪切率，a是颗粒半径，Kbt是热能。对于ϕ=0.40时的硬球悬浮液，文中还给出了预测微结构和等效模拟结果的实例，以供比较。在软胶体的模拟中，预测的对分布函数与剪切诱导有序化转变开始之前的模拟很好地吻合。根据预测的微观结构计算的剪切粘度也与模拟结果基本一致。在所提出的理论背景下，讨论了流体动力相互作用在流致结构中的作用。
A previously developed Smoluchowski theory for concentrated hard-sphere suspensions in shear flow is extended to study structure and rheology of colloidal suspensions with soft repulsive interactions. Accelerated Stokesian Dynamics simulations are carried out to provide insight and to enable direct comparison with theoretical predictions. The effect of extended range repulsive interactions is studied by considering repulsive interactions with different steepness, using identical potentials in simulation and theory, for varying shear rates characterized in dimensionless form as 0.1 ≤ Pe ≤ 100; here, Pe = 6πηa3/kbT is the ratio of hydrodynamic to Brownian forces and η is the fluid viscosity, is the shear rate, a is the particle radius and kbT is the thermal energy. Examples of predicted microstructures and the equivalent simulated results for hard-sphere suspensions at ϕ = 0.40 are also presented for comparison. The predicted pair distribution function is in good agreement with simulations before the onset of a shear-induced ordering transition in simulations of the soft colloids. The calculations of shear viscosity based on the predicted microstructure were also in general agreement with simulation results. The role of hydrodynamic interactions on flow-induced structures is discussed in the context of the proposed theory.