Three-dimensional simulations of incompressible fluid flow within hydrocyclone have been performed using the developed numerical technique. A discretization of the physical problem has been done by using a finite element method based on mixed approximation of the velocity and pressure space. The approach offers significant advantages in the solution process of convection dominated internal flows having one inlet and more than one outlet. It deals with the complex geometry of the head entry part of hydrocyclone. The boundary conditions represent forces and are efficiently incorporated into the numerical formulation. Such formulation is very useful since it allows modeling the characteristic velocity profile in the outlet. We investigate the interaction between the swirling flow and velocity profile at the outlet. The studies are carried out for fluids with different properties and can be extended to hydrocyclones with different geometrical configurations. (c) 2005 Elsevier B.V. All rights reserved.