The spacing of spur dikes is an important consideration for the layout of spur dike channels. This study focuses on the local scour morphology and flow field characteristics of spur dikes with different spacings. The results show that the maximum scour depth is generally found in the vicinity of the first spur dike head. With the increase of the spacing of spur dikes, the shielding effect of the first spur dike is weakened. The maximum velocity in the main flow zone is twice that of the approach flow velocity in the fixed bed. But it is approximately the same as the incoming velocity in equilibrium scouring. The maximum turbulent energy appears to be mainly located in the backflow area of the fourth spur dike in the fixed bed, while the maximum value appears at the second spur dike head in the movable bed. Further, the shear stress decreases as scouring develops. Pearson correlation analysis was carried out between scour depth and shear stress. The analysis results are significantly correlated, indicating that the bed shear stress plays a prominent role in the scouring process. These discoveries can serve as a guide to determine the most reasonable spacing of spur dikes.

Advances in computer technology have facilitated the use of large-eddy simulation (LES) as a numerical simulation method in fluid mechanics. In this study, LES was used for the numerical simulation of curved water flow with a large curvature. The simulation results show that water separation occurs near the convex bank of the bend transverse section while the separation area increases and then decreases along the water depth direction, where the peak is at half-depth. As the water surface is affected by air shear stress, the velocity decreases. However, as the gradient increases, the vorticity is larger and the vorticity distribution is more even. Reflux occurs in the inlet and outlet sections of the bend but does not occur on the surfaces of z/H = 0.5 and z/H = 0.2, where the vorticity distribution is uneven. In the narrow corridor of the concave and convex banks, notably near the curved top, vorticity distribution is concentrated with a high intensity. At the center of the curve, the vorticity intensity is weak but 10 times higher at the concave and convex banks. A strong correlation exists between circulation structure and vorticity distribution: the vorticity is large where the circulation is intense and the structure is complex.