Multiphase flows of particles in non-newtonian systems

本研究的重点是工业利益的粒子流体系统的性质，应用于创建功能设备或薄膜涂层的涂层流。 薄壁和微注塑成型、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。 我们寻求更好地了解在薄液体聚合物薄膜和成型颗粒沉积，粘附和团聚的机制。 在这项研究中，颗粒-固体和颗粒-流体相互作用的性质将进行研究，考虑到碰撞，胶体，和流体动力学的力量，与颗粒和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针对特定性能进行定制。 例如，可以设计结合颗粒和第二材料相的薄粘合剂膜，以增强氧气和水的阻隔性能;或者，可以在平面和横向方向上模制具有高导电性的导电部件。 我们需要更好地理解由于流动、颗粒表面性质和自由表面的作用而产生的竞争力，这些都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一个有价值的工具。复杂流体的模拟结合了许多颗粒，高度亚结构的材料，和非线性流变学是一个具有挑战性和开放性的问题。 具有实际数量的粒子的系统的计算工作仍然是巨大的，并且将研究流体-粒子耦合的最佳方法以最小化计算工作。 这项工作的结果预计将用于开发高附加值的制造产品，如：槽涂着色聚合物薄膜（用于感光器），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).