Suspensions of fumed silica in polypropylene glycol exhibit shear-thickening under steady shear and "strain-thickening" under oscillatory shear. Strain-thickening refers to a sharp increase in the complex viscosity eta* observed at critical combinations of strain-amplitude and frequency. Two regimes of strain-thickening behavior have been found: The first occurs at high critical strains and low...

We show that bent-core liquid crystalline materials exhibit non-Newtonian flow in their optically isotropic liquid phase. We conjecture that this behavior is due to the existence of nanostructured, fluctuating clusters composed of a few smectic-like layers. Shear alignment of these clusters explains the shear thinning observed in bent-core liquid crystals having either a nematic phase or nonmod...

Rheological studies of the ceramic based concentrated titania nanoparticle dispersions showed a clear correlation between molecular structure of the cationic polymers used as dispersants and the viscosity of the slurries. Dynamic viscosity of the electrostatically stabilized alkaline (pH 10.0) dispersions of the bare titania nanopowders with a solid loading of 15 – 25 wt.% was rather high (abou...

Non-Brownian suspensions present a transition from Newtonian behavior in the zero-shear limit to a shear thickening behavior at a large shear rate, none of which is clearly understood so far. Here, we carry out numerical simulations of such an athermal dense suspension under shear, at an imposed confining pressure. This setup is conceptually identical to recent experiments of Boyer, Guazzelli, ...

The rheological behavior of metallic alloys containing both solid and liquid phases is investigated in the low solid fraction range (<50%). This behavior depends on both the solid fraction and the shear rate. The concept of Effective Volume Fraction (EVF) is used to decorrelate the influence of these two parameters. At high shear rate the slurry behaves like a suspension of hard spheres, wherea...

We study the pinch-off dynamics of droplets of yield stress and shear thinning fluids. To separate the two non-Newtonian effects, we use a yield stress material for which the yield stress can be tuned without changing the shear thinning behavior, and a shear thinning system (without a yield stress) for which the shear thinning can be controlled over a large range, without introducing too much e...

The static and dynamic (complex) shear viscosity of a single-layer dusty plasma is measured by applying, respectively, a stationary and a periodically modulated shear stress, induced by the light pressure of manipulating laser beams. Under static conditions we observe a decrease of the viscosity with increasing shear rate, the so-called shear-thinning behavior. Under oscillating shear both the ...

The current understanding is that the non-Newtonian rheology of active matter suspensions is governed by fluid-mediated hydrodynamic interactions associated with active self-propulsion. Here we discover an additional contribution to the suspension shear stress that predicts both thickening and thinning behavior, even when there is no nematic ordering of the microswimmers with the imposed flow. ...

Colloidal suspensions exhibit shear thinning and shear thickening. The most common interpretation of these phenomena identifies layering of the fluid perpendicular to the shear gradient as the driver for the observed behavior. However, studies of the particle configurations associated with shear thinning and thickening cast doubt on that conclusion and leave unsettled whether these nonequilibri...

The Direct Simple Shear (DSS) test is one of the laboratory element testing devices that has been widely used to assess soil behavior. Although the DSS test is considered to simulate the cyclic shear loading mode from the earthquakes in an effective manner, the most commonly used versions of the test device (such as the NGI-type DSS device) do not provide means of measuring the lateral stresses...