thermodynamic pressure of the gas, was investigated recently in [@Pun08].

Recent RHIC results give a strong indication that in the heavy-ion collisions experiments, a hot dense matter can be formed [@reff1]. Such an experimental evidence might agree with the “new state of matter” as predicted in the Lattice QCD simulations [@reff5]. However, the experimentally observed elliptic flow in peripheral heavy-ion collisions seems to indicate that a thermalized collective QCD matter has been produced. In a addition to that, the success of ideal fluid dynamics in explaining several experimental data e.g. transverse momentum spectra of identified particles, elliptic flow [@reff6], together with the string theory motivated that the shear viscosity $\eta$ to the entropy $s$ would have the lower limit $\approx 1/4\pi$ [@reff7] leading to a paradigm that in heavy- ion collisions, that a [*nearly*]{} perfect fluid likely be created and the quarks and gluons likely go through relatively rapid equilibrium characterized with a thermalization time less than $1$ fm/c [@mueller1].

According to recent lattice QCD simulations [@mueller2], the bulk viscosity $
\xi $ is not negligible near the QCD critical temperature $T_c$. It has been shown that the bulk and shear viscosity at high temperature $T$ and weak coupling $\alpha_s
