Shear viscosity of liquid copper at experimentally accessible shear rates: Application of the transient-time correlation function formalism

2008 ◽  
Vol 128 (8) ◽  
pp. 084506 ◽  
Author(s):  
Caroline Desgranges ◽  
Jerome Delhommelle
Keyword(s):  
Correlation Function ◽  
Shear Viscosity ◽  
Liquid Copper ◽  
Time Correlation ◽  
Time Correlation Function ◽  
Transient Time ◽  
Shear Rates ◽  
Function Formalism

scholarly journals Shear viscosity of massless classical fields in scalar theory

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Hidefumi Matsuda ◽  
Teiji Kunihiro ◽  
Akira Ohnishi ◽  
Toru T Takahashi
Keyword(s):  
Correlation Function ◽  
Shear Viscosity ◽  
Early Stage ◽  
Classical Field Theory ◽  
Dense Matter ◽  
Scalar Fields ◽  
Time Correlation ◽  
Time Correlation Function ◽  
Classical Field ◽  
Slow Decay

Abstract We investigate the shear viscosity of massless classical scalar fields in the $\phi^4$ theory on a lattice by using the Green–Kubo formula. Based on the scaling property of the classical field, the shear viscosity is represented using a scaling function. The equilibrium expectation value of the time-correlation function of the energy–momentum tensor is evaluated as the ensemble average of the classical field configurations, whose time evolution is obtained by solving the classical equation of motion starting from the initial condition in thermal equilibrium. It is found that there are two distinct damping time scales in the time-correlation function, which is found to show damped oscillation behavior in the early stage around a slow monotonic decay with an exponential form, and the slow decay part is found to dominate the shear viscosity in the massless classical field theory. This kind of slow decay is also known to exist in molecular dynamics simulations, so it may be a generic feature of dense matter.

Sechν(bt) FORM OF THE MEMORY FUNCTION

2002 ◽  
Vol 16 (20) ◽  
pp. 739-745 ◽  
Author(s):  
SHAMINDER SINGH ◽  
C. N. KUMAR ◽  
K. TANKESHWAR
Keyword(s):  
Thermal Conductivity ◽  
Correlation Function ◽  
Shear Viscosity ◽  
Sum Rules ◽  
Memory Function ◽  
Time Correlation ◽  
Time Correlation Function ◽  
Lennard Jones ◽  
Special Cases ◽  
Auto Correlation Function

An expression for the memory function appearing in the Mori's memory function formalism has been derived using two plausible approximations. The resulting expression is of the [Formula: see text] form. The parameters a, b and ν are such that sum rules up to the sixth order of an appropriate time correlation function are exactly satisfied. The sech (bt) and the [Formula: see text] forms of the memory function have been used and derived earlier. But these satisfy sum rules only up to the fourth order and are special cases corresponding to ν = 1 and ν = 2. It is found that ν varies from 1.1 to 1.7 for Lennard–Jones fluids, investigated over wide ranges of densities and temperatures for the velocity auto-correlation function. We have also derived expressions for the shear viscosity and the thermal conductivity by using this approach. The results obtained for the shear viscosity and the thermal conductivity for Lennard–Jones fluids at various densities and temperatures have been found to be in good agreement with molecular dynamics (MD) results.

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