The Simplest Complex Fluid? The Remarkable Rheology of Hard-sphere Suspensions
Dense suspensions of solid spherical particles in a Newtonian liquid solvent provide a crucial basic model system for development of mixture flow and complex fluid theory. By complex fluid, we mean that there is a dependence of the properties of the fluid upon the shear rate. In practice, suspensions and slurries appear in coatings, ceramic precursors, mud flows, among numerous examples.