Due to the importance of channel flow characteristics in the water conveyance, the study of it is a noteworthy problem for hydraulics experts and much attempts has been accomplished for the modeling of the flow characteristics. One signifcant problem in this respect is the secondary flow cells and their effect on flow specifcations. Widespread experimental and analytical investigations have been accomplished on this phenomenon. However, researchers are trying to replace the expensive and time-consuming experimental approaches and ad hoc analytical models with numerical simulation procedures using computational fluid dynamics (CFD). Selection of the proper turbulence model is one of the most important problems for this type of the numerical modeling. In the present study, after evaluating several turbulence models including k–ε, shear stress transport (SST) and three versions of the Reynolds stress model (RSM) (i.e. LRR-IP, LRR-QI, and SSG models), for the numerical simulation of the secondary flow cells and their effects on trapezoidal channels flow, the more efcient model was selected. Available experimental data and theoretical model was used to validate the selected urbulence model. The results were validated in terms of the free water surface, depth-averaged velocity, and boundary shear stress. The results confrmed the performance and efciency of SSG version of the Reynolds stress model for the numerical modeling of the secondary flow cells
