Crossover between equilibrium and shear-controlled dynamics in sheared liquids.
We present a numerical simulation study of a simple monatomic Lennard-Jones liquid under shear flow, as a function of both temperature T and shear rate .gamma. By investigating different observables we find that (i) there exists a line, T(.gamma), in the (T-(.gamma)) plane that sharply marks the border between an "equilibrium" and a "shear-controlled" region for both the dynamic and the thermodynamic quantities; and (ii) along this line the structural relaxation time, tau(alpha)(T(.gamma)), is proportional to .gamma(-1), i.e., to the typical time scale introduced by the shear flow. Above T(.gamma), the liquid dynamics is unaffected by the shear flow, while below T(.gamma) both T and .gamma control the particle motion.
Angelani
L
L
Dipartimento di Fisica and INFM, Università di Roma La Sapienza, Piazzale Aldo Moro 2, 00185 Rome, Italy.
Ruocco
G
G
Sciortino
F
F
Tartaglia
P
P
Zamponi
F
F