Numerical study of statistically developed gas-liquid intermittent flows by the lens of three-dimensional simulations

Abstract

Two-phase intermittent flows are characterized by an alternation between a region almost fully occupied by liquid (a liquid plug) and another one composed by a gas bubble. This type of flow is frequently found in industry, particularly in the transportation of oil and gas through pipelines. Their dynamics is commonly modeled with a one-dimensional approach, since long pipelines are employed, making 2D or 3D simulations unfeasible. The models always require an assessment of wall and interfacial friction factors, which are usually obtained by empirical correlations. In this work, from full 3D velocity fields across statistically developed slug unit cells, flow parameters needed for 1D models were determined. For that, several three-dimensional numerical simulations were performed using the open source platform OpenFOAM®. The two-phase flow was determined within a computational domain corresponding to a single slug unit cell, with periodic boundary conditions under imposed pressure gradient and overall void fraction, employing the Volume of Fluid (VOF) method. Both laminar and turbulent flows were studied. Turbulence was modeled with the k-ω Shear Stress Transport (SST) model. The axial velocity profile along the cross section, as well as slug parameters, were compared with available experimental data, showing a quite good agreement. From the results validated by experimental data, friction factors and momentum flux parameters were determined, allowing the development of corrections to improve the available 1D models.