THERMODYNAMIC NONEQUILIBRIUM IN LIQUID-VAPOR FLOWS

This paper explores the method of internal variables, which is used to describe the nonequilibrium state between a liquid and its vapour in two-phase flows. The actual dryness fraction, chosen as an internal va riable, is introduced to the model by means of a relaxation equation. A one-dimensional system of conservation equations supplemented by the relaxation equation is applied in order to predict the pressure distr ibution during flashing flow along a divergent channel. A second evolu tion equation containing the diffusive term is developed to predict th e propagation of a pressure pulse in a two-phase flow mixture.