Modelling of two-phase flow through concentric annuli

A mathematical model is introduced in order to predict the flow characteristics of multiphase flow through an annulus. Flow patterns and frictional pressure losses estimated using the proposed model are compared with the experimental data of a wide range of liquid and gas flow rates recorded at a flow loop consisting of numerous circular pipes and annulus. The results showed that the model predictions for flow patterns and frictional pressure losses are reasonably accurate. Moreover, it is observed that geometry and liquid phase viscosity have a significant influence on flow pattern transitions and frictional pressure losses