Multiphase flows of particles in non-newtonian systems

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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).