Numerical Study of the Effects of Inlet Geometry on the Performance of the Sediment Bypass Tunnel using SSIIM Numerical Model

Document Type : Original Article


1 Assistant Professor, Department of Civil Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Iran.

2 Assistant Professor, Department Water Engineering, Garmsar Branch, Islamic Azad University, Garmsar, Iran.

3 Associate Professor, Department of Water and Environmental Engineering, Civil Engineering Collage, Shahrood University of Technology, Shahrood, Iran.


Sediment Bypass Tunnels (SBTs) are deviant channels that convey the current containing sediments from the upstream to the downstream of the reservoir. This study investigates the effect of hydraulic and geometry parameters such as discharge, flow depth and deviated channel width on the deviating of the flow and sediment to the SBTs. In addition, the effects of the submerged plates with angels 30o, 45o, and 60o on the sediment transport to the 90-degree deviated channel (SBTs) examined. The laboratory experiments conducted in the flume with 10.0 m long, 0.60 m width and 0.75 m height. Moreover, the SSIIM model used to simulate flow and sediment. The results revealed that the 33% reduction of diversion channel width would lead to an 8.5% reduction of the deviated flow to the deviated channel. The maximum performance of deviated channel was obtained when the Froude number decreased and the flow depth increased. In terms of the angle of submerged plates, it can be observed that increasing the Froude number by 0.3 results in a 22.2% decrease in the channel deviated discharge and a 53.3% decrease in the channel deviated sediment. By reducing the Froude number of the flow and the depth along with using submerged plates at an angle of 30 degrees, the optimal diversion option can be provided. The comparison results of the numerical simulation of the SSIIM model with experiment data indicated that it simulated deviated flow and sediment to the SBTs with the correlation coefficient more than 0.95.


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