Hyperbolicity breaking model and drift-flux model for the prediction of flow regime transition after inverted annular flow

The concept of hyperbolicity breaking is applied to predict the flow regime transition from Inverted Annular Flow (IAF) to Agitated Inverted Annular Flow (AIAF). The resultant correlation has the similar form to Takenaka's empirical one. To validate the proposed model, it is applied to predict Takenaka's experimental results using R-113 refrigerant with four different tube diameters of 3, 5, 7 and 10 mm. The proposed model gives accurate predictions for the tube diameters of 7 and 10mm. As the tube diameter decreases, the differences between the predictions and the experimental results in crease slightly. The flow regime transition from AIAF to Dispersed Flow (DF) is described by the drift flux model