Nondimensional groups were identified and correlations were established to initialize flash-boiling spray for use in Lagrangian/Eulerian spray simulations. The objective was realized through CFD simulations with nonequilibrium interphase heat transfer and an Eulerian-Eulerian spray model. Parametric studies were carried out on 2D axisymmetric straight and stepped nozzles to study the effects of geometric and operating conditions on the near-nozzle spray. The effects of the inlet corner radius, nozzle diameter, counter-bore diameter and the inner nozzle length were assessed along with the effects of varying injection and ambient pressures and the fuel temperature as part of this study. The influence of these parameters on the coefficient of discharge, the spray-cone angle, and the Sauter mean diameter (SMD) were analyzed both qualitatively and quantitatively. Results indicate that the inlet corner radius dominates the coefficient of discharge; the time available for the fuel to vaporize determines the magnitude of the spray-cone angle. The SMD is dominated by the extent of the fuel superheat, defined as a ratio of the ambient to the saturation pressure of the fuel. The established correlations were incorporated using a user-defined function as a means to initiate flash-boiling Lagrangian spray. The simulated downstream spray angle and SMD were validated against experimental results.