Constitutive Equations for Two-Fluid Model Used in Thermal-Hydraulic Analyses

Abstract

In recent years, the two-fluid model has often been used in thermalhydraulic analyses. This model is considered to be theoretically more strict and to be more relevant in treating such two-phase flow phenomena as these that are affected by thermal or hydrodynamic non-equilibrium, because the model describes the conservation of mass, momentum and energy for both gas and liquid phases, separately. In order for the model to display its real worth, however, it is important that the constitutive equations be used properly. This review paper, therefore, presents the constitutive equations for flow-regime transitions, interfacial area concentration, behavior of liquid droplets, interfacial friction, interfacial heat transfer, wall friction and wall heat transfer that are actually used in computer codes for thermal-hydraulic analyses.