A finite volume model was built upon earlier work with the aim of simulating free surface flows, pressurized flows and their simultaneous occurrence (mixed flows) in single-liquid and two-phase flow conditions (entrapment and release of air pockets). The model presented herein is based on a two-governing equation model. Three main contributions are presented herein, namely: (1) the ability of the proposed model to simulate mixed flows without restriction of the flow type in the free surface region (e.g., supercritical flow), (2) extension of our single-phase flow model for simulating the entrapment and release of air pockets, and (3) formulation of an approach for handling numerical instabilities that may occur during numerical pressurization of the flow. The model presented herein is robust and simulates any transient-mixed flow condition for realistic pressure wave celerities.
León, Arturo S.; Ghidaoui, Mohamed S.; Schmidt, Arthur R.; and García, Marcelo H.. (2010). "A Robust Two-Equation Model for Transient-Mixed Flows". Journal of Hydraulic Research, 48(1), 44-56. http://dx.doi.org/10.1080/00221680903565911