A computational fluid dynamic model is used to analyze the transport processes of a passive scalar generated in the mixing of two fluids or flows in a pipeline x-junction. Turbulent flow field is computed for the merging of streams using two and three-dimensional simulations, which are achieved employing Cartesian coordinates, BFC and a cut cell method. These different numerical solving methods are compared. The numerical model is validated through an experimental set-up. Different parameters are measured for various operating conditions. The influence of the angle between pipe inlets is studied to establish the optimal condition in which the passive scalar concentration in both outlets is similar.