Relativistic nuclear hydrodynamics and phase transition to the deconfinement state

The possible formation of nuclear matter in the phase of a quark--gluon plasma in relativistic heavy-ion collisions is considered in the framework of a hydrodynamic approach. The main results are obtained in a single-fluid model of the formation of a baryon-enriched plasma and relate to nuclear collisions at energies up to 10 GeV/nucleon. At higher energies, a two-fluid model predicts the formation of a plasma in the fragmentation region, but the baryon density is much lower. In all the investigations, including scaling hydrodynamics in the baryon-depleted region of intermediate rapidities, allowance is made for a delayed phase transition to the deconfinement state. A generally covariant formulation of relativistic hydrodynamics is presented as a useful numerical method, together with some extensions of the methods of the standard theory (selection of comoving coordinates, allowance for sink terms, and two-fluid interaction)