Water lubricated transport of high viscous oil is one of the energy efficient technologies in the energy sector. In the present work, a computational fluid dynamic study has been performed to simulate core annular downflow through vertical pipes. The CFD software package FLUENT 6.3.26 [1] is used and a satisfactory match between the simulated data and experimental results has been obtained. A comprehensive study has been made to generate the profiles of velocity, pressure, volume fraction and wall shear stress over a wide range of inlet oil and water velocities. (C) 2010 Elsevier B.V. All rights reserved.