Drift Flux Model Parameters Estimation based on Numerical Simulation of Slug Flow Regime with High-Viscous Liquids in Pipelines

Multiphase flow models involve more variables than available equations, thus constitutive equations are required to solve the system's governing equations. In the Drift Flux Model, mean drift velocity of the gas phase is estimated by using a Dispersed-Phase Distribution Coefficient and Gas Drift Velocity closure relationships. This study investigates the hydrodynamic of the slug flow regime with high-viscous liquids, and develops an equation for the Distribution Coefficient. Simulation cases were run with inclination angles varying from 0° (horizontal direction) to 90° (vertical upward) and a 0.051m-ID pipe. OpenFOAM, an open-source CFD software, was used to numerically solve the two-phase flow problem. A detailed methodology to estimate drift flux parameters from the data stored at each grid block is presented. This step-by-step methodology allows researchers to further develop the constitutive equations for Distribution Coefficient and the Drift Velocity for other cases. Simulated results were compared with experimental data from the literature and other published models for horizontal and vertical pipes. The results showed that this CFD modeling approach is suitable for representing actual slug flow in pipes. The newly developed Distribution Coefficient constitutive equation has less than 10% absolute average relative error for the viscosity range of 0.14 to 1.120Pa·s, and pipe inclinations from 0° to 90°.