Dm. Heyes et Pj. Mitchell, NONEQUILIBRIUM MOLECULAR AND BROWNIAN DYNAMICS SIMULATIONS OF SHEAR THINNING OF INVERSE POWER FLUIDS, Molecular physics, 84(2), 1995, pp. 261-280
The shear thinning behaviour is compared of model atomic and colloidal
liquids computed using molecular dynamis (MD) and Brownian dynamics (
ED) simulations, respectively. Apart from the equations of motion, oth
er quantitative features of the two models are identical. Using an int
ernal standard time scale, derived from the integral of the normalized
linear stress relaxation function, it is shown that there are signifi
cant differences in the normalized shear thinning curves and the assoc
iated assembly restructuring under shear of the two model liquids. The
hexagonal string phase appears approximately at a value of half shear
thinning for the MD system, whereas the ED liquid manifests the strin
g phase only at much higher equivalent shear rates at the onset of the
second Newtonian plateau. These differences are explained in terms of
the more 'sluggish' dynamics of the model colloidal system, derived f
rom their inertialess equations of motion. Other thermodynamic and mec
hanical properties of the model liquids are shown to reflect the relat
ive reluctance of the ED liquid to form the string phase, when compare
d with the MD liquid.