Numerical investigation of the coherent structures in a curved channel with a spur dike at different angles with respect to the flow directions Available to Purchase

Secondary currents formed by river meanders induce scour along the river's outer bank if the bed material is erodible. Spur dikes are constructed along the outer reach of these rivers to control the flow and prevent erosion of the outer bank. Within the bending portion of a strongly curved channel, many streamwise-oriented vortices develop. The existence of a spur dike, on the other hand, causes the formation of additional coherent structures, such as horseshoe vortices and wake vortices. The interactions between these vortices and the secondary circulation produce a highly three-dimensional complicated flow environment within the channel bend and around the spur dike. In order to analyze coherent structures and their interactions with one another, eddy resolving turbulence model, Detached Eddy Simulation was used in this study. Several spur dike configurations, namely 45°, 90°, and 135° with respect to the flow direction, were investigated to better understand the changes in the flow field and coherent structures in a 180° channel bend with flat bed. The orientation and strength of the coherent vortex forming at the center of the channel changes with the inclusion of the spur dike. There are considerable changes in the bed shear stress distribution for different spur dike orientations. Among all, the 90° spur dike appears to be the most suitable one as the area prone to large bed shear stress value is 14.2 times smaller, whereas the maximum bed shear stress is 18% smaller compared to the case without the spur dike.