The effects of curvature on flow structure in river bends

In this study, the focus is on understanding the effect of curvature on the three-dimensional flow structure in a channel bend using large-eddy simulations. A key non-dimensional geometric parameter that influences the flow structure is the ratio of the radius of curvature to the top width of the uniform flow upstream of the bend R/T_w. Four highly-resolved large-eddy simulations of 180^o bends were performed with R/T_w. ranging from 1.25 to 8.7, encompassing tight to mild bends. Analysis of simulation results show that on average, the maximum shear stresses for tight bends are closer to the inner bank and shift closer to the outer bank in the interior of the channel bend. Furthermore, it is clear that the flow structure evolves from the beginning of the bed to a more developed condition beyond 90^o into the bend. This research is aimed at contributing towards fundamental understanding of the flow structure in river bends using computational simulations.