Exact and Approximate Solutions Describing Expansion of Relativistic Ideal Fluid
Solutions of the relativistic hydrodynamical equations are studied, which describe expansion of the relativistic ideal fluid with linear equation of state (EOS) p=ke. In case of the extremely stiff EOS (k=1) we present a method of generation of exact solutions; some special solutions are obtained describing spherical and non-spherical expansion. For 0.2 < k < 1 we found a representation of spherically symmetric ultra-relativistic radial outflow in a form of an asymptotic series in negative powers of radial variable. The representation is used to obtain solutions for radial outflow with outgoing shock waves.