Suspensions are of wide interest and form the basis for many smart fluids. For most suspensions, the viscosity decreases with increasing shear rate, that is, they shear thin. Few are reported to do the opposite, that is, shear thicken, despite the longstanding expectation that shear thickening is a generic type of suspension behaviour. Here we resolve this apparent contradiction. We demonstrate...

We investigate the rheology of dilute dispersions of fumed colloidal particles with attractive interactions in hydrocarbon liquids. Surprisingly, these systems display shear thickening due to the breakdown of densified flocs and a concomitant increase in the effective volume fraction of the fractal particles in the fluid. We show that this shear thickening is controlled by a critical stress and...

Dense suspensions under sufficiently high shear stress can exhibit a dramatic transition to a solidlike state. This is known as extreme shear thickening and is sometimes accompanied by dilatancy. This behavior is contradictory; the material is solidlike but only when flowing. To probe the elasticity of the dilatant state, we measure the transient inertio-elastic oscillations that occur in respo...

– We present a simple phenomenological model to describe shear-thickening in a wormlike micelle solution. The solution is assumed to undergo a reaction above a critical shear stress, to form a gel-like phase. There is no flow within this “gel” phase, and it is insoluble in the solution. The amount of gel in the system is determined by a competition between a stress-dependent reaction rate, whic...

Ceramic powder (zirconia) was mixed with binder consisting polypropylene, paraffin and stearic acid in elastic extruder. Steady and oscillatory shear flow properties of these materials in the molten state were measured on a cone-plate rheometer; parallel superposed steady and oscillatory shear flow experiments were also carried out. Moreover, flow properties at high shear rates were measured on...

The deformation of red blood cells in microvessels was investigated numerically for various vessel diameters, hematocrits, and shear rates. We simulated blood flow in circular channels with diameters ranging from 9 to 50 μm, hematocrits from 20% to 45%, and shear rates from 20 to 150 s(-1) using a particle-based model with parallel computing. The apparent viscosity predicted by the simulation w...

Reducing hemolysis has been one of the major goals of rotary blood pump development and in the investigational phase, the capability of hemolysis estimation for areas of elevated shear stresses is valuable. The degree of hemolysis is determined by the amplitude of shear stress and the exposure time, but to date, the exact hemolytic behavior at elevated shear stresses and potential thresholds fo...

Attractive emulsions near the colloidal glass transition are investigated by rheometry and optical microscopy under shear. We find that (i) the apparent viscosity eta drops with increasing shear rate, then remains approximately constant in a range of shear rates, then continues to decay; (ii) the first normal stress difference N1 transitions sharply from nearly zero to negative in the region of...

The nanosized magnetite particles were synthesized by means of a coprecipitation method and used to prepare the aqueous ferrofluids with various volume fractions. The magnetorheological properties of the aqueous ferrofluids have been investigated as a function of magnetic field. Under steady-state shear, the apparent viscosity for all of the ferrofluids exhibited a shear thinning behavior. But ...

The yielding behavior of hard sphere glasses under large-amplitude oscillatory shear has been studied by probing the interplay of Brownian motion and shear-induced diffusion at varying oscillation frequencies. Stress, structure and dynamics are followed by experimental rheology and Browian dynamics simulations. Brownian-motion-assisted cage escape dominates at low frequencies while escape throu...