  We use a connection between relativistic hydrodynamics and scalar field
theory to generate exact analytic solutions describing non-stationary
inhomogeneous flows of the perfect fluid with one-parametric equation of state
(EOS) $p = p(\epsilon)$. For linear EOS $p = \kappa \epsilon$ we obtain
self-similar solutions in the case of plane, cylindrical and spherical
symmetries. In the case of extremely stiff EOS ($\kappa=1$) we obtain
''monopole + dipole'' and ''monopole + quadrupole'' axially symmetric
solutions. We also found some nonlinear EOSs that admit analytic solutions.
