Numerical Simulation of 3D Flow Structure and Turbulence Characteristics near Permeable Spur Dike in Channels with Varying Sinuosities

Abstract

Owing to the different degrees of bending in rivers in nature, it is difficult to conduct experiments in situ. In this study, the renormalization group (RNG) k-ε turbulence model in ANSYS Fluent was used to analyze the three-dimensional flow structure and turbulence characteristics near a spur dike and to evaluate the variation trend of flow in rivers with different degrees of bending. The results show that in channels with different curvatures, the vortex appears between the spur dikes and is disturbed by the permeable hole, and the backflow area moves downstream. The strength of secondary flow (SSF) fluctuates greatly in the vicinity of the spur dike and the downstream region, and the peak value appears 3.22 m (21.5 times L) away from the inlet of the bend. The SSF increases as the bend curvature increases. The SSF displays similar variation trends in the three kinds of bends. The peak value of normalized turbulent kinetic energy (NTKE) appears 3.14 m away from the entrance of the bend, the NTKE is the largest in the 45° bend and the smallest in the 180° bend, and it decreases only at distances of 3.25–4.19 m away from the entrance of the bend as the bend curvature increases.