Suspensions of non-Brownian particles in complex fluids: Rheology, microstructure and fluid mechanics*

Suspensions of non-Brownian particles in complex fluids (hereafter complex slurries) are relevant in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). It is also relevant to mention that some biological and smart materials can be designed from various suspensions, drawing attention to applications in physiology, bio-locomotion and shock absorbers. This countless number of suspensions has a wide range of nonlinear rheological behaviors, such as shear thinning, shear thickening, shear banding, yield stress, and finite normal stress differences even when inertia is negligible.

This talk will introduce an array of experimental and modeling techniques that my research team uses to investigate rheological properties and fluid dynamical behavior of the complex slurries. The goal is to establish a continuum framework and refine it through a series of microstructure investigations. This continuum framework is formulated and explained via a mean field study, homogenization theory, as well as a computational study based on the Immersed Boundary Method. In addition, it will be presented that how confinement effects transition a suspension from one rheological behavior to another and how these observations can be explained beyond the framework of the mean field approaches. Finally, open questions will be disclosed, which must be answered in order to build a firm foundation for a long-term contribution to the area of complex slurries.