Side weir is an effective control in streams. To study geometrical dimensions effect of the weir on the generated flow structure, here, experimental and numerical simulation analysis of the previous and present experimental studies was done on the flow around different geometric types of side weir. A triangular labyrinth side weir with three distinct included angles (θ = 30o, 45o, and 60°) and three weir heights (P = 10, 15 and 20 cm) has been tested, in addition normal rectangular side weir for comparison. The volume of fluid (VOF) approach was used for tracking free-surface subcritical flow conditions at the centerline of the main channel and near side weir banks. Accurate results were discovered by employing the Renormalization Group (RNG k-∈) turbulence model with the experimental outcomes. The smallest inclusion angle of side weir, generates smaller width of vortices zone near the upstream side weir wall which obstacles only a smaller length of crest as compared to the larger inclusion angle that hindrances larger length of this side for flowing water. In addition the contribution portion of the surface flow for the smallest inclusion angle which is indicated by streamlines is about 0.66 times the main channel width. Moreover, the maximum width of separation zone at the downstream of the main channel reached to 0.8 times the width of the main channel for the triangular labyrinth side weir. The stagnation point exists at the downstream end of side weir results the increase of surface elevation to reach maximum level. The coefficient of discharge of such weirs were 3.8, 2.7 and 2.12 times the coefficient of the normal rectangular side weir for θ = 30o, 45o and 60°, respectively.