Computer Simulation of Flow Behaviors of Concentrated Suspensions

浓缩悬浮液表现出复杂的流变性，如触变性和触变性。根据传统的胶体科学，这些行为都是由内部结构的一定变化引起的。然而，究竟形成了一种什么样的“结构”，与流变性质有何关系等基本问题都没有得到明确的回答。在本课题中，我通过计算机模拟研究了剪切流中浓缩式悬架的结构，主要研究了硬球系统和集料系统两个系统。在前一种情况下，流体动力相互作用是重要的，而在后一种情况下，接触胶体之间的内聚力是必不可少的。对于每种情况，都提出了一个新的模型来实现模拟。关于结构和宏观流变学的详细信息。得到了它们的性质。一个特别有趣的结果是，在聚集球系统中，当浓度超过一定的临界浓度时，球形成一个无限大的网络，但粘度保持有限。这表明集合体的大小是决定粘度的关键因素。作为本研究的副产品，发展了一种关于浓缩型乳状液的新理论，其中界面动力学是重要的。

Concentrated suspensions show complex rheological properties, such as thixotropy and rheopexy. According to traditional colloid science, these behaviors are caused by a certain change of internal "structure". However, basic questions such as what kind of "structure" is actually formed, and how it is related to rheological properties have not been answered clearly. In this project, I studied the structure of concentrated suspension in shear flow by computer simulation.Two systems are studied, the hard sphere system and the aggregating system. In the former case, the hydrodynamic interaction is important, and in the latter, the cohesive force between the touching colloids is essential. For each case, a new model is proposed to enable the simulation. The detailed information on the structure and the macroscopic rheological. properties are obtained. A particularly interesting result is that in the aggregating sphere system, the spheres form an infinitely large network when the concentration exceeds a certain critical concentration, but the viscosity remains finite. This indicates that the size of the aggregate is the key factor in determining the viscosity.As a byproduct of the present research, a new theory has been developed on the concentrated emulsions in which the dynamics of interface is important.