Evaluation of a Hyperbolic Conservative Mixture Model for Thermal-Hydraulics Two-Phase Flows of Nuclear Reactors

Paper i proceeding, 2017

This paper briefly presents simulation results of a hyperbolic model of the two-phase flow equations written in a conservative form and discretized using finite volume methods. The model presented herein utilizes mixture properties and constitutes a three governing equations model. Such a model able to treat the relative motion between phases independently. Godunov methods of centred type are used for the convection terms. The TVD SLIC scheme is used in which the fluxes are calculated by the Riemann problem. The key results include the ability of the model to simulate two-phase flows with strong gradients in both velocity and phase fractions. In particular, the model is robust and reproduces with fair accuracy the complete wave structure associated with the flow variables. The model and the methods are capable of handling numerical instabilities that may occur during simulations, which is essential in analysis of two-phase flow phenomena in nuclear reactors. The model in hand is considered promising for future consideration of additional sub-models describing complex mechanisms governing gas-liquid mixture two-phase flow including thermodynamic non-equilibrium (subcooled boiling), heterogeneous volume fraction and mass fraction fields for the gas phase.