Slope effect on stability of stratified two-phase flow

The modeling of transient liquid/gas interface in a two-phase stratified flow through a horizontal or nearly-horizontal circular duct has been investigated. A one-dimensional two-fluid model for horizontal flows, based on a set of non linear hyperbolic governing equations, was considered. Each phase is characterized by its equations of conservation written in dimensionless form. The method of characteristics combined with an explicit method is used to simulate the flow. The model accounts for the pipe inclination effects. It is shown that, an upward inclination leads to a more probable slug flow, whereas negative values of the slope induce a more stable stratified flow.