Two-phase flow analyses are critical to successful design and operations of two-phase and multiphase pipe flow applications found in major industrial fields, such as petroleum, nuclear, chemical, geothermal and space industries. Due to difficulties in obtaining analytical transient solutions, approximate solutions have been applied to two-phase pipe flow. However, these approximate solutions neglect convective terms in two-phase Navier-Stokes equations. The aim of this current study was to develop transient tools to predict transient two-phase pipe flow. The objectives of this study were to develop a simplified transient model and to validate the proposed model with published experimental data. A simplified transient two-phase pipe flow model was obtained in this study by simplifying the two-phase Navier-Stokes equations. The simplified equations include: (i) a transient continuity equation of combined two-phase flow that includes two new dimensionless terms; (ii) transient two-phase momentum equations that account for convective terms only; and, (iii) a steady state pressure gradient
