https://doi.org/10.1140/epja/i2016-16117-y
Letter
Estimation of the shear viscosity from 3FD simulations of Au + Au collisions at 
= 3.3-39 GeV
1
National Research Centre “Kurchatov Institute”, 123182, Moscow, Russia
2
(Moscow Engineering Physics Institute), National Research Nuclear University “MEPhI”, 115409, Moscow, Russia
* e-mail: Y.Ivanov@gsi.de
Received:
15
January
2016
Revised:
4
April
2016
Accepted:
11
April
2016
Published online:
2
May
2016
An effective shear viscosity in central Au+Au collisions is estimated in the range of incident energies 3.3 GeV 
39 GeV. The simulations are performed within a three-fluid model employing three different equations of state with and without the deconfinement transition. In order to estimate this effective viscosity, we consider the entropy produced in the 3FD simulations as if it is generated within the conventional one-fluid viscous hydrodynamics. It is found that the effective viscosity within the different considered scenarios is very similar at the expansion stage of the collision: as a function of temperature (T) the viscosity-to-entropy ratio behaves as 
; as a function of the net-baryon density (
), 
, i.e. it is mainly determined by the density dependence of the entropy density. The above dependences take place along the dynamical trajectories of Au+Au collisions. At the final stages of the expansion the 
/s values are ranged from 
at the highest considered energies to 
at the lowest ones.
© The Author(s), 2016
