Study of Counteracting the Secondary Flow in Open Channel ‎Bends

Abstract

This thesis comprises of three parts, part 1 presents the study of the main hydraulic features of flow as super-elevation, velocity distribution, and the secondary flow using Large Eddy Simulation (LES) without any protection for the bed and banks. In this part, a suitable turbulent model is chosen in addition to checking of the capability of this model. The results of a previous laboratory experiments are used to validate the predicted results from the numerical model. Part 2 aims to study the efficiency of a new protection technique (water screen) to counteract of the secondary flow numerically in addition to choosing the optimum flow ratio for this technique. Part 3 presents the suitable transverse location of the new technique close/a way the outer bank in the curved open channel. The results reveal that LES and realizable k-ε turbulent models are capable to predict the main flow characteristics for the curved open channel. The new technique (water screen) can counteract the curvature-induced secondary flow on condition that the induced flow from tube is not less than 20 % of main flow. The position of water screen effect on the secondary circulation cell. The new technique has a negative effect on the outer bank if the distance is increased away the outer bank.