A semi-implicit numerical scheme for a transient two-fluid three-field model on an unstructured grid

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapor field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been adapted for an unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified ICE scheme is robust and predicts the phase changes and the flow transitions due to a boiling and a flashing very well.