Evolution of the quark-gluon and hadronic fluid with the compressible bag model

The evolution of matter produced in nucleus collisions is investigated in the frame work of the simplified fluid equation, where the compressible bag model is used as the equation of state for hadrons. It is shown that the quark-gluon phase is easily achieved in RHIC experiments, and that the typical structure of the phase transition, however, may be difficult to observe in simple analyses of $<p_t>$ data.