This paper describes a numerical study of two-phase, strongly swirling flow in a cylindrical separator with double vortex generators to predict the separation efficiency of a mixture consisting of oil as the primary phase and sand, with a specific diameter, as the secondary phase. The mixture-granular multiphase and RNG k-epsilon turbulence models are implemented in this study. The analytical predictions are compared against experimental data; i.e., the mean tangential velocity and the mean radial pressure profiles. The overall agreement between the experimental data and the predictions obtained with the RNG k-epsilon model are reasonably good. The numerical procedure has the ability to capture a narrow localized residence zone for the solid particles at a periphery location near the mid-separator where the two vortices merge and the suspension process occurs. Moreover, the analysis has proven to be useful in predicting the internal flow structure of the primary phase, thereby, the separation of the particulate phase. The separated particles are forced to remain near the periphery of the cylindrical separator and being concentrated at the mid-separator as a result of the strong centrifugal force. (C) 2007 Elsevier Ltd. All rights reserved.