Generating new solutions for relativistic transverse flow at the softest point

Using the method of prolongation we generate new solutions from a simple particular solution for relativistic transverse flow with cylindrical symmetry in 1+3 dimensions. This is an extension of the longitudinal Bjorken flow ansatz and can be applied among others during first order phase transition in an expanding system. The prolongated solution allows for tracing back the flow profile from a transverse flow conjectured at the end of phase transition at CERN SPS heavy ion collisons.