On the modelling of multidimensional two-phase flows

One of the current challenges in modelling of two-phase flows is the ability to predict the detailed spatial distribution of phases in complex geometries. The phase distribution in a fuel assembly of a nuclear reactor is the key parameter, which determines the reactor safety and performance. In particular, such limiting phenomena as the Critical Heat Flux or the onset of two-phase flow instability can not be predicted with the required accuracy if the detailed phase distribution in the fuel assembly is not known. The purpose of this work is to present a mechanistic multi-field model for the prediction of two-phase flows in an arbitrary channel. The averaged conservation equations and proper closure relationships for interfacial terms are shown. The model is applied for the prediction of phase distribution in bubbly and slug flows in pipes and between two parallel walls, where most experimental data exist. The numerical results were compared against experimental data and good agreement has been obtained.