Confluences are often observed in natural and artificial channels. Open-channel confluences have complex hydrodynamics due to the development of secondary currents, mixing layer, and flow separation zone. CFD modeling is an important tool used for understanding the behavior of complex flow patterns near the confluence. Construction of physical models is generally not economically feasible; in that case, numerical models are conveniently used to evaluate and predict performance. For representing the large range of flows existing in nature or industry, several numerical and turbulence models have been developed in the last three decades. Through numerical simulation of the flow behavior in an open-channel confluence in OpenFOAM, this study attempt to address this problem. To assess how well various turbulence models reproduce the flow characteristics of a 90º open-channel confluence, which has a common and simple geometry, a three-dimensional numerical model is set up. The flow behavior has been simulated using the finite volume method (FVM). The governing equation for the study is the Reynolds-averaged Navier–Stokes equation and three different turbulence models namely standard k–ε model, realizable k–ε model, and k–ω were employed in this study. The accuracy of simulation results from three different turbulence models (the standard k–ε model, the realizable k–ε model, and k–ω) has been evaluated by comparing velocity fields. A rigid-lid method was used to treat the water surface. Regardless of the rigid-lid approach's inherent incapacity to mimic the free surface, the numerical model's general flow behavior was in good accord with the experimental results. However, the helicoidal current and secondary current downstream of the junction were not accurately reproduced by any of the turbulence models. There is no appreciable difference has been found in the performance of the standard k–ε, realizable k–ε, and the k–ω models. However, statical analysis recommends that the realizable k–ε turbulence model is more reliable in predicting complex flow geometries such as in the case of the confluence of flow than the k–ω turbulence model and the standard k–ε turbulence model.