Friday, April 19, 2013

1304.4993 (Wen Zheng et al.)

Signatures of shear thinning-thickening transition in dense athermal
shear flows

Wen Zheng, Yu Shi, Ning Xu
In non-equilibrium molecular dynamics simulations of dense athermal shear flows, we observe the transition from shear thinning to shear thickening at a crossover shear rate $\dot\gamma_c$. Shear thickening occurs when $\frac{{\rm d (ln} T_g)}{{\rm d (ln}\dot\gamma)}>2$ with $T_g$ the granular temperature. At the transition, the pair distribution function shows the strongest anisotropy. Meanwhile, the dynamics undergo apparent changes, signified by distinct scaling behaviors of the mean squared displacement and relaxation time on both sides of $\dot\gamma_c$. These features serve as robust signatures of the shear thinning-thickening transition.
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