Discontinuous shear thickening (DST) observed in many dense athermal suspensions has proven difficult to understand and to reproduce by numerical simulation. By introducing a numerical scheme including both relevant hydrodynamic interactions and granularlike contacts, we show that contact friction is essential for having DST. Above a critical volume fraction, we observe the existence of two sta...

The nonequilibrium molecular dynamics computer simulation method was used to study microsegregated block copolymer systems in a selective solvent under a shear flow field. Two polymer concentrations were considered, 0.3 and 0.4, corresponding to the body centered cubic spherical and hexagonal cylindrical zero-shear phases, respectively. As the shear rate increased, both systems exhibited two-st...

The dynamic orientation behavior of the lamellar phase of a triblock copolymer is studied in a wide range of shear rates as a function of solvent composition. We find that various phases can be induced by increasing the shear rate. At low shear rates, the onion phase forms from planar lamellae with many defects. A further increase of the shear rate caused the onion structure to break down, and ...

[1] We report on laboratory friction experiments in which simulated faults are exposed to shear velocity oscillations at different amplitudes and frequencies. Granular layers are sheared in a servo-controlled biaxial apparatus at constant normal stress and background shear velocity, with a shear velocity sinusoid superimposed. Correlation between oscillations and stick-slip events is determined...

We use Brownian dynamics simulations in combination with the umbrella sampling technique to study the effect of shear flow on homogeneous crystal nucleation. We find that a homogeneous shear rate leads to a significant suppression of the crystal nucleation rate and to an increase of the size of the critical nucleus. A simple, phenomenological extension of classical nucleation theory accounts fo...

The purpose of this study was to understand bacteria profile modification and its applications in subsurface biological operations such as biobarrier formation, in situ bioremediation, and microbial-enhanced oil recovery. Biomass accumulation and evolution in porous media were investigated both experimentally and theoretically. To study both nutrient-rich and carbon-source-depleted conditions, ...

The shear dependent location of the isotropic-nematic spinodals in suspensions of bacteriophage fd is studied by means of time resolved birefringence experiments. The hysteresis in the birefringence on increasing and subsequently decreasing the shear-rate allows the determination of the location of points in the shear-rate vs concentration phase diagram between the isotropic-to-nematic and the ...

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...

Shear-thickening behavior and shear-induced pattern formation have been observed in semidilute starch solutions. While the shear-thickening behavior is due to breaking up of highly concentrated gel-like structures dispersed in dilute starch solutions, the pattern-forming behavior is not well understood. The pattern formation, observed when the starch solution is exposed to a high shear field, i...

The design and construction of an apparatus for studying the simultaneous small angle neutron scattering (SANS) and steady shear viscosity behavior of polymer melts and concentrated solutions is discussed. Successful operation of the device is demonstrated on a blend of 20 weight percent deuterated polystyrene and 80 weight percent poly(vinylmethylether). The effects of shear on the critical be...