Numerical study of the effect of discharge on flow pattern around a submerged spur dike in an open channel

One of the important purposes of river engineering science is to protect river banks from erosion phenomenon and to prevent shifting of the main channel path. Spur dike is a hydraulic structure which has a lot of applications for stabilizing river banks and increasing water depth. According to widespread use of this structure, it is important to understand the flow pattern around it. Since flow pattern around a spur dike is complex and fully 3D, 3D simulation was done in this study. FLOW-3D software was employed to simulate the flow around a submerged spur dike. VOF method was used for free surface simulation and RNG k-ε model was used for turbulence modeling. Based on comparison of numerical and experimental results for stream wise velocity component and flow depth, it was concluded that numerical model could simulate the flow parameters with relatively high accuracy. In following, the effect of discharge increase on velocity profiles and flow free surface was investigated. According to obtained results, maximum longitudinal velocity Infront of the spur dike nose and flow depth at the upstream of spur dike increased with discharge increase. In lower discharges, the changes rate was more and vice versa. Also, the ratio of the flow depth at the upstream and the flow depth at the downstream increased with discharge increase.