3-DIMENSIONAL FLOW STRUCTURE AT OPEN-CHANNEL DIVERSIONS

An experimental investigation of the flow structure at a 90-degrees open-channel diversion is presented. Velocity data obtained in a laboratory flume show that the flow at an open-channel diversion is three-dimensional, exhibiting similar characteristics to river bend flows. The behavior of three-dimensional features, including the dividing stream-plane and the strength of a secondary circulation, were found to depend upon the roughness of the main channel bed and the ratio of diversion flow velocity to main flow velocity. Results of this study indicate that a description of sediment-transport behavior at diversions requires the understanding of the three-dimensional flow structure and the application of sophisticated modeling techniques. The results also suggest a strong analogy between diversion flows and bend flows. The similarity between diversion and bend flows may justify the application of relatively simple bend-flow models to predict the three-dimensional flow features at open-channel diversions.