Multiphase flows are commonly encountered in oil and gas industries. The transport of multiphase flow causes the formation of slug, the increase of pressure drop and the possibility of phase changes therefore, a set of simulation runs was performed to predict flow regimes in a horizontal pipeline, and the results were compared with the Baker chart. The effects of small downward inclinations of pipelines on the formation of slugs were also considered.Volume of Fluid model (VOF) has been used to predict the flow regimes in a horizontal pipeline within an 8-cm diameter and 7-m length pipe. In order to identify the critical parameters of slug flow (mean slug frequency, slug translational velocity, hold up and pressure drop), the simulations were carried out in a 7.63-cm diameter and 5-m length pipe mounted with three different inclination angles of 0 ,-0.5 and -0.8 . A good agreement between CFD model and experimental data has shown the advantage ofÂ Â VOF model for studying two-phase flows.