Due to the tailwater depth downstream of hydraulic structures, supercritical flow is changed to a subcritical flow regime, by establishing a hydraulic jump. This phenomenon results in high intense turbulent flow, air entrainment and energy dissipations, leading to destruction of the downstream canals and hydraulic structures. Therefore, design engineers might prefer to exclude the hydraulic jump from super- to subcritical flow due to unfavorable flow conditions. Recently a number of analytical-experimental studies have been performed to investigate the possibility of such transition by applying a convex bed as a transition structure. They concluded that the proposed transition structure is able to eliminate the hydraulic jump, for the range of Froude numbers between 1.3 and 4.5. In the present study the flow filed along and downstream of the transition region from super –to subcritical flow without a hydraulic jump was simulated using an open source OpenFOAM software. We investigated the ability of further transition structures to eliminate the hydraulic jump in the transition from super- to subcritical flow, for the range of Froude numbers between 2.14 to 6.4, based on a numerical modelling. The flow free-surface was modeled using volume of fluid (VOF) method. According to the former studies and based on a trial and error procedure, among different turbulent models, RNG k-? turbulent model was found to be the most appropriate one to analyze these type of open channel flows. Primarily, the experimental models studied by Kabiri-Samani et al. (2014) were simulated numerically and the results were validated and compared to those of the model experimentation. Based on a verification analysis we obtained good agreement between the numerical and experimental results. Consequently, for a wide range of supercritical approach flow Froude numbers, we conducted different numerical models and the possibility to exclude the hydraulic jump, for the defined scenarios was explored. Accordingly, the 3-D velocity component profiles and turbulent characteristics of flow along and downstream of the transition region were obtained. Results show that by increasing the supercritical approach flow Froude number up to 6.4, shock and oblique waves are formed at the free-surface. Finally, we analyzed the flow characteristics such as velocity profiles, turbulence intensities and Reynolds stresses over the transition structures in details. Keywords : Supercritical flow, Subcritical flow, Hydraulic jump, OpenFOAM, Turbulence model