• friction factor
• MAST
• multi-field model
• slug flow
• two-phase flow

During this doctoral activity, developed at TEA Sistemi SpA with the contribution of the University of Pisa in the context of an R&D project funded by ENI E&P, the formulation of a new set of liquid-wall and gas-liquid interfacial friction factor correlations was performed. The attention was focused on the improvement of existing correlations when applied to the design of long transportation pipelines.
In this aim, a new set of data related to nitrogen-water flow in a 80 mm pipe operating at pressures in the range 5-25 bar has been used along with data published in the open literature (mainly concerning air-water flows at atmospheric pressure). These data were used to develop new correlations for friction factors in horizontal stratified gas-liquid flow conditions.
Moreover a new multi-field model called MAST (Multiphase Analysis and Simulation of Transition), recently developed at TEA Sistemi SpA with the support of ENI E&P and addressing the Oil&Gas field, was presented in detail during this activity and validated against experimental measurements for the investigation of the long slug flow sub-regime.