The transport phenomena in Siemens reactors has been investigated by using computational fluid dynamics (CFD) technique. The reaction kinetics was validated against two data sets of silicon epitaxial deposition experiments. Comparative simulations were carried out for four types of reactors with different configurations of gas supplying nozzles and offgas ports. The uniformity index was introduced to evaluate rod growth uniformity. The result showed that improper gas distributing system would result in zones of low velocity together with high temperature, and uneven species concentration distribution, finally cause low uniformity of rod growth. The reactor with a single offgas port at the center of the bottom plate was supposed to be best design among the four from both the performance and the equipment complexity points of view. (C) 2018 Elsevier Ltd. All rights reserved.