Two-Dimensional Analysis of Air–Water Interaction in Actual Water Pipe-Filling Processes

This paper investigates air–water interactions during a controlled filling process of an actual water pipeline using a two-dimensional Computational Fluid Dynamics (CFD) model. The main objectives are to understand the dynamic interaction of these fluids through water inflow patterns, pressure pulses, and air-pocket dynamics based on contours. This study uses an existing cast iron pipeline 485 m in length, a nominal diameter of 400 mm, and an air valve with a nominal diameter of 50 mm. The methodology of this CFD model includes the Partial Volume of Fluid (pVoF) method for air–water interface tracking, a turbulence model, mesh sensitivity and numerical validation with pressure and velocity measurements. Results highlight the gradual pressurization of pipelines and air pocket behavior at critical points and show the thermodynamic interaction concerning heat transfer between gas and liquid. This study advances the application of CFD in actual water pipelines, offering a novel approach to air pocket management.