Progress in two-phase flow modeling: Interfacial area transport

Abstract

The interfacial area transport equation (IATE) employs a dynamic approach to predict interfacial area concentration (IAC) in two-phase flows. It eliminates the need for the static flow regime transition criteria and flow regime dependent IAC correlations used in closing the two-fluid model and therefore any potential artificial bifurcation or numerical oscillations stemming from these static correlations. The efforts to develop the IATE are reviewed in this work, focusing on studies within the past decade. The current state-of-the-art in IATE is a two-group interfacial area transport equation that is applicable to predict interfacial area concentration from bubbly to churn-turbulent flows. An extensive experimental database has been established in literature for various two-phase flow conditions. The database is used to develop constitutive models to close the IATE and to validate its performance. These include adiabatic and heated conditions, vertical and horizontal flow orientations, channels with flow restrictions, round, rectangular, annulus, and rod-bundle geometries, and normal-gravity and reduced-gravity conditions. IATE has been implemented into practical system analysis codes such as TRACE and computational fluid dynamics (CFD) codes such as CFX and Fluent to evaluate its performance. In addition, the recent efforts of extending the IATE beyond churn-turbulent flow to churn-annular transition and annular flows are also reviewed. These include the new instrumentation, experimental database, and additional constitutive models to predict annular flows.