In the present study, effects of different configurations of the laminarizer including inlet, vortex finder and both inlet and vortex finder on the separation efficiency, pressure drop, tangential velocity, and 50% cut size are analyzed. The computational fluid dynamics (CFD) method is applied to predict and demonstrate the flow field inside both conventional cylindrical style and square cyclones. The Reynolds stress model (RSM) is used to simulate the turbulent flow field. Particle trajectories are calculated via discrete phase model (DPM). The discrete random walk (DRW) model is used to model the turbulent dispersion of particles. The results show that installing both inlet and vortex finder laminarizers has the most effect on increasing separation efficiency compared to other configurations of the laminarizer. The cyclone with both inlet and vortex finder laminarizers has the smallest 50% cut size in both conventional and square cyclones. Installing the laminarizer caused a minor increase in the pressure drop for all cases. By installing the laminarizer at inlet and vortex finder simultaneously, a minor increase of about 4.6% and 6.4% is obtained for conventional and square cyclones at the inlet velocity of 18 m/s, respectively. Also, installing the laminarizer at both inlet section and vortex finder of conventional and square cyclones reduced the 50% cut size at inlet gas velocity of 18 m/s about 8% and 27%, respectively. This reduction proved that using the laminarizer in the square cyclone was more effective than the conventional cyclone. (C) 2018 Elsevier B.V. All rights reserved.