Space-time Evolution of Quark-Gluon Plasma Fluid with First Order Phase Transition

We numerically solve the (3+1)-dimensional relativistic hydrodynamical equation with a bag-model equation of state, which is one of the simplest models for the first order phase transition. Based on the numerical solution, we discuss the space-time evolution of the hot fluid produced in ultra relativistic nuclear collisions. Especially, the space-time structure of the two-phase co-existing region during the quark-gluon plasma-hadron phase transition is analyzed in detail. Finally, we investigate the change of the mass spectra of $J/\psi$, ${\eta}_{c}$ and ${\phi}$ as possible experimental signatures of the phase transition.