Advances in the characterization of transient two-phase flow

A new algorithm to characterize transient two-phase flow with phase change has been introduced. A mixture of water and steam in which the disperse phase was assumed to be homogeneously distributed in the numerical cells, was considered. the AUSM +-up scheme was also extended to two-phase flow, which is characterized by its robustness when dealing with low Mach number flows. The ability of the AUSM +-up scheme to compute fast-depressurization processes accompanied by a flashing of the liquid phase was also proven. The scheme was found able to predict the pressure drop at steady state, the volume fraction at the exit, and the onset of boiling. Some spurious oscillations were observed in the pressure field at the outlet and at the point at which the onset of boiling takes place.