Multiphase flows of particles in non-newtonian systems

本研究的重点是工业兴趣的颗粒流体系统的性质，应用于用于创建功能装置或薄膜涂层的涂层流。薄壁和微注塑、浸涂和槽涂都是高附加值器件开发中使用的主要加工技术。我们试图更好地了解颗粒沉积，粘附和团聚的机制，在薄液体聚合物薄膜和成型。在本研究中，将研究颗粒-固体和颗粒-流体相互作用的性质，考虑碰撞，胶体和水动力，颗粒与流场之间的双向耦合。其中一个具有挑战性的领域将是非牛顿流体效应的结合，因为许多涂层涉及聚合物流体或熔体中的颗粒分散。我们还试图了解材料中的流动诱导结构，其中颗粒和聚合物基质的组织可以根据特定性能进行定制。例如，人们可以设计一种结合颗粒和第二种材料相的薄胶膜，以增强氧气和水的阻隔性能；或者，导电组件可以在平面和横向方向上具有高导电性。我们需要更好地理解由于流动、颗粒表面特性和自由表面的作用而产生的竞争力，它们存在于所有这些应用中。模拟将为理解这些竞争效应的作用提供有价值的工具。复杂流体的模拟包含许多颗粒、高度亚结构材料和非线性流变学，是一个具有挑战性和开放性的问题。具有实际粒子数的系统的计算工作量仍然很大，因此将研究流体-粒子耦合的最佳方法以减少计算工作量。这项工作的结果预计将用于开发高附加值的制成品，例如：槽涂层着色聚合物薄膜（用于光感受器），浸涂光纤扩散器（用于癌症治疗）和导电模塑产品（例如传感器）。

The focus of this research is on the nature of particle-fluid systems of industrial interest as applied in coating flows for the creation of functional devices or thin film coatings. Thin wall and micro injection molding, dip and slot coating are all major processing technologies used in the development of high value added devices. We seek to better understand the mechanism of particle deposition, adhesion, and agglomeration in thin liquid polymer films and moldings. In this research, the nature of the particle-solid and particle-fluid interactions will be studied, taking into account the collision, colloidal, and hydrodynamic forces, with two way coupling between the particles and the flow field. One of the challenging areas will be the incorporation of non-Newtonian fluid effects, as many coatings involve particle dispersion in polymer fluids or melts. We also seek to understand flow induced structure in materials where the organization of the particles and polymer matrix can be tailored for specific properties. For example, one could design a thin adhesive film that incorporates particles and a second material phase to enhance oxygen and water barrier properties; or, an electrically conductive component could be molded with high conductivity in the planar and transverse directions. We need to better understand the competing forces due to flow, particle surface properties and the role of free surfaces, which exist in all these applications. Simulation will provide a valuable tool in understanding the role of these competing effects. The simulation of complex fluids combining many particles, highly substructured materials, and nonlinear rheology is a challenging and open problem. Computation effort for systems with realistic numbers of particles is still massive, and the best approaches for fluid-particle coupling will be investigated to minimize computational effort. The results of this work are anticipated to be used to develop high value added manufactured products, such as: slot coated pigmented polymer films (for photoreceptors), dip coated fiber optic diffusers (for cancer therapy), and electrically conductive molded products (e.g. sensors).