Separation characteristics of dispersed oil-water pipe flows—CFD modelling and experiments.*

The separation of liquid-liquid dispersions in pipes is common in many industrial sectors. However, it is challenging to predict the characteristics of the flow evolution due to the complex interfacial nature of separation mechanisms. Therefore, in this study, experiments along with Design of Experiments (DoE) techniques and Computational Fluid Dynamics (CFD) simulations were performed to investigate the flow of silicone oil and water in a horizontal pipe. Several cases with different mixture velocities (0.52- 1.04 m/s) and oil fractions (15%-60%) have been explored. OpenFOAM (version 8.0) was used to perform Eulerian-Eulerian simulations coupling with the population balance models. Good consistency is observed between the simulated and experimental results. The blending factor in the OpenFOAM solver is found to impact the simulation. Also, it may provide a feasible compensation mechanism for the mesoscale uncertainties of drop-drop coalescence models. Overall, this study aims to improve the physical understanding of drop-drop and drop-interface coalescence and the evolving characteristic layers during the separation of a dispersed flow.