International Conference on Mechanical, Industrial and Energy Engineering 2018 23-24 December, 2018, Khulna, BANGLADESH * Corresponding author. Tel.: +88-01761919895 E-mail addresses: abir.hasan.kuetme@gmail.com Oil flow Water flow ICMIEE18-2280 CFD Analysis of Two-Phase (Oil-Water) Flow in Horizontal Pipe Md. Abir Hasan * , Mohammad Ilias Inam Department of Mechanical Engineering, Khulna University of Engineering & Technology, Khulna-9203, Bangladesh ABSTRACT In this paper, the behaviors of two-phase (oil-water) flow in horizontal pipe have been investigated numerically using ANSYS Fluent 16.1. For these simulations for oil-water stratified flow, Volume of Fluid (VOF) model and RNG k-ε turbulence model is adopted. A number of simulations have been carried out for different inlet velocity (0.5m/s, 1.0m/s, 1.5m/s, 2.0m/s, 2.5m/s and 3.0m/s) and for different volume fraction (vf) of oil (10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% and 90%). Numerical results demonstrate that pressure drop (P) and wall shear stress (), both, are increasing with respect to inlet velocity and volume fraction of oil. A series of empirical relations were also developed to show the effect of inlet velocity and volume fraction of oil on the pressure drop and wall shear stress. Keywords: CFD Simulation, VOF model, Two-phase flow, Oil-water, Pipe flow. 1. Introduction Analysis of immiscible liquid-liquid two-phase flow in pipes has been a subject of intense research for several decades due to its fundamental significance as well as much related industrial application, especially in the petroleum and process industries. Though liquid-liquid flow systems play very significant roles in the petroleum and other industries, however very less attention has given as compared to the gas-liquid flow systems. Now-a-days, liquid-liquid flow systems have attracted more and more interest in the offshore oil industry. Typically immiscible liquid-liquid two-phase, i.e. oil–water, flow occurs in the co-current manner of in petroleum products transportation since oil and water are mostly produced at the same time. The transportation of crude oil is very important in the offshore facilities, where the oil is transported using pipelines to the processing facility. Figure 1.1: Oil Water two phase flow in horizontal pipe. The water present in the crude oil significantly affects the transportation of petroleum oil from the well to an onshore platform [1]. The oil transportation pipes lie on the seabed in either horizontal or inclined way. During the transportation process, the variation in water or oil volume fraction in the pipes can have a significant influence on pumping power required to pump the fluid, due to the change in the pressure drop across the pipeline. The presence of water in the pipe has a significant effect on the transportation of mixture of oil and water from the reservoir to the onshore or processing platform since the behavior of liquid two- phase flow in tubes behaves differently from single- phase flow [2]. For variable mixture velocities and the water volume fraction, the fluid might have different flow regimes in the pipe, which might influence the input power requirement during the pumping of the mixture. 2. Literature Review Lots of works have been carried on water and oil two- phase flow in straight horizontal pipes in last two decades. Angeli et al. (1998) experimentally studied the pressure gradients for the co-current flow of low viscosity oil-water in horizontal pipes (D = 0.0254 m), made of stainless steel and acrylic resin, for different velocities and water volume fractions. It was found that at high Reynolds number, where dispersed flow patterns occur, there was a peak in pressure gradient during phase inversion and an apparent drag reduction affect when oil is the continuous phase [3]. Gao et al. (2003) numerically studied the pressure drop, liquid holdup, the axial velocity, and slippage, for the oil-water two-phase flow in the straight horizontal pipe and also verified with experimental data in the literature. Stratified water oil oil-water flow in a straight horizontal pipe is simulated numerically with VOF model. The simulation is done in a time-dependent way and the final solution which relates to steady-state flow is studied [4]. Elseth et al. (2001) experimentally study the behavior of flow of oil-water in the horizontal straight pipe (D =0.0508m). Pressure drops, slip ratio, velocity profiles, turbulence distributions and liquid holdup are measured