Amin Mahmoudi

Rivers change their paths over time, and the changes in their longitudinal and transverse sections cause them to converge and diverge. This phenomenon brings about many changes in the fow pattern and, as a result, the scour pattern. Therefore, the investigation of the changes to the river path in the form of convergence and divergence is one of the interesting issues to river engineers. This study investigated the efect of diferent convergence and divergence ratios of 5, 10, 15, and 35% during a 180° bend on the number of changes in the fow pattern by using a SSIIM numerical model. The results demonstrated that the trends of changes in the power of the secondary fow during uniform, converging, and diverging bends were similar, and with increase in the convergence and divergence of the bend, the power of the secondary fow decreased and increased, respectively. The maximum power of the secondary fow occurred in the bend with 35% divergence and increased by 1.26%, compared to the bend with 35% convergence. At the apex of the bend, by increasing the bend convergence from 5 to 35%, the value of the secondary fow power decreased by about 12.3%.