The modulation of the re-circulation region is one of the primary interests of this numerical study. This study investigates the modulation of the re-circulation zone behind a square obstruction by a single inclined turbulent wall jet with varying angles of attack. The flow field is visualized using the post-processing system of the simulation software and the results have been analyzed. The experiments are carried out for different angles of attack of the wall jet and a range of high Reynolds numbers. The results show that the re-circulation zone is significantly affected by the angle of attack of the wall jet. The maximum length of the re-circulation zone decreased with increasing angle of attack. The wall jet angles of attack (AOA) also affect the strength and position of the vortex structures in the re-circulation zone. The results of this study provide insights into the use of inclined wall jets for controlling the flow field behind obstructions in engineering applications such as flow control and mixing enhancement. The numerical simulation is based on a two-phase volume of fluid (VOF) model with open channel boundary conditions. The standard k–ω SST turbulence model is applied to solve the Reynolds averaged equation.