This work presents a Computational Fluid Dynamics calculation to evaluate the effects of cone dimensions on the performance, hydrodynamics and centrifugal forces of sampling aerocyclones (gas cyclones). The problem of modeling highly swirling flow is overcome by means of an algebraic turbulence model. The axial and tangential velocities in a cyclone are successfully simulated. The refined mesh on the cyclone cone was also applied to ensure a better prediction on the effect of cone tip diameter to its performance, centrifugal forces and hydrodynamics. The pressure drop, grade efficiency and cut-off size of a cyclone of different cone dimensions was predicted very well with average deviation of about 2.9%, 5% and 2.1% respectively from experimental data presented in the literature. The findings suggest that the higher peak of tangential and axial velocity in a cyclone of a small cone lead to a higher collection efficiency and pressure drop. This helps to assess the benefit of enlarging or reducing the cone of a given cyclone. Results obtained from the computer modeling have demonstrated that CFD is suitable for modeling an effect of cyclone dimension on its performance. (c) 2005 Elsevier B.V. All rights reserved.