The Effects of Viscosity on Hydrodynamical Evolution of QGP

Abstract

The space-time evolution of Quark Gluon Plasma at RHIC energies under circumstance of nonideal fluid dynamics with cylindrical and spherical symmetry are studied. Using RHLLE numerical method, we compute the bulk and shear viscosity components in addition to temperature and radial velocity profiles. The numerical results show that the effect of shear viscosity cause to slow down of expansion of system and reducing of longitudinal pressure due to shear viscosity lead to an increasing in radial velocity profiles. These effects on cylindrical geometry are more remarkable than spherical geometry. The space-time diagrams of thermal freeze-out show that a softened equation of state leads to a larger space time of freeze-out and it will be a little larger while we take the effect of viscosity into account. The two-pion Hanbury-Brown-Twiss (HBT) interferometry for the viscous hydrodynamic sources is performed. The HBT analyses indicate that the viscosity effect on the two-pion HBT results is small if only the shear viscosity is taken into consideration in the calculations. The bulk viscosity leads to a larger transverse freeze-out configuration of the pion-emitting sources, and thus increases the transverse HBT radii. The results of the longitudinal HBT radius for the source with Bjorken longitudinal scaling are consistent with the experimental data.