A horizontal stratified gas-liquid two-phase flow model for the two-fluid model in the WCOBRA/TRAC-TF2 PWR safety analysis code

The adequacy of the horizontal stratification model is confirmed by examining the predicted flow regime in a horizontal pipe with the measured data of the high pressure TPTF two-phase flow experiments. The void fractions for the horizontal flow are predicted with a good accuracy, which indicates that the interfacial drag and the wall drag in the two-fluid model are properly modeled and the two-fluid momentum equations with the hydraulic slope term reasonably capture the influence of inlet and outlet boundary conditions expected in the PWR LOCA simulation.