Comparative analysis of wall shear stress models to the drift-flux model applied to slug flow regime

The one-dimensional drift-flux model efficiently predicts gas-liquid flows dominated by gravity force. The advantages of the drift-flux model applied to pipe flows are the absence of interfacial terms, well posedness and the reduced number of transport equations, but its weakness lays on the constitutive laws to predict the wall shear force of a gas-liquid mixture. Its success on upward vertical slug flows is, in part, due to the fact that for gravity dominated flows the friction contribution to the pressure gradient is usually small. In these applications the accuracy of the wall shear force model is not dominant. A challenging aspect is the application of the drift-flux model to the horizontal slug flows where the pressure gradient is due to friction force. The objective of this work is to develop a comparative analysis among wall shear stress models applied to the one-dimensional, steady state drift-flux approach applied to gas-liquid mixture flowing in the slug regime. Effective viscosity models based on the homogeneous and also on empirical propositions are employed. Additionally it is also introduced a mechanistic wall shear stress model. The effect of the use of distinct wall shear models into the drift-flux model is assessed by comparing the estimated pressure gradients against experimental data.