Numerical Modeling of Two-Phase Flows Using Advanced Two Fluid Systems

The purpose of this paper is to report on the development and assessment of approximate Riemann solver methods for the discretization of non-linear non-conservative systems arising in the simulation of two-phase flows. These methods are able to treat general two-phase flow systems with realistic state equations and are flexible enough to be applied on any mesh type, structured as well as unstructured. We will detail models that go from the basic 6 equation two-fluid model to the coupling of this system with one or more transport equations, for instance on volumetric interfacial area concentration, or on partial void fractions of groups of bubbles (MUlti-Size-Group model). This kind of transport equation is useful to predict at a finer level the interfacial patterns or bubble size distribution and takes account of coalescence or breakup rates of inclusions. We make a glimpse at the choices made regarding this aspect. Different physico-numerical benchmarks are provided in order to illustrate the numerical and physical modeling. Confrontation with experimental or analytical reference data are performed whenever possible. Computer simulations are performed using OVAP, a new multidimensional CFD code.