A comparison of standard k–ε and realizable k–ε turbulence models in curved and confluent channels

Bends and confluences are often observed in rivers, and one of the phenomena that characterize flows in open channel bends and confluences is secondary current. Instead of moving somewhat parallel to the channel axis, the movement of the fluid particles in curved and confluent channels takes a spiral path. In this paper, a 3D OpenFOAM numerical model is employed to simulate the effect of secondary currents on water velocity in channel bends and confluences. The behavior of these currents is simulated by using the finite volume method (FVM). The experimental data of a sharply curved channel and a confluent channel were used to compare the numerical results and to evaluate the validity of the model. To assess the performance of different models in predicting the behavior of these secondary flows, two turbulence models (i.e., standard k–ε and realizable k–ε) were applied in the current study, and the accuracy of the standard and realizable k–ε turbulence models was evaluated and discussed. The results of this study showed the better performance of the standard k–ε model in curved channels and the realizable k–ε model in confluent channels.