Comparison of computational fluid dynamics simulations and experiments for stratified air-water flows in pipes

Stratified gas-liquid flow is a flow regime typically encountered in multiphase pipelines. The understanding and modeling of this regime is of engineering importance especially for the oil and gas industry. In this work, simulations have been conducted for stratified air-water flow in pipes. We solved the Reynolds-averaged Navier-Stokes (RANS) equations with the volume of fluid (VOF) method. The aim of this work was to evaluate the performance of the k-ω shear stress transport (SST) turbulence model with and without damping of the turbulence at the gas-liquid interface. Simulation results were compared with some of the latest experimental results found in the literature. A comparison between the simulated velocity and kinetic energy profiles and the experimental results obtained with the particle image velocimetry (PIV) technique was conducted. The characteristics of the interfacial waves were also extracted and compared with the experiments. It is shown that a proper damping of the turbulence close to the interface is needed to obtain agreement with the experimental pressure drop and liquid hold-up. In its current form, however, RANS with the k-ω turbulence model is still not able to give an accurate prediction of the velocity profiles and of the interface waves.