Investigation of the Flow Resistance in Armed Culvert with Asymmetric W Shaped Weirs

Construction of diversion dams in the rivers has caused many changes in these areas; so, hydraulic structures prevented the fish migration to the upstream. Then, the construction of hydraulic structures as fish-path for energy dissipation and improving the fishes passage are necessary. In the present study, asymmetrical W shaped Weir are designed with the tip angle of 40 °, and the barriers with 30°, 60°, are designed with the tip angle of 90°. To recognize the hydraulic performance of fish-path, three physical models were designed for any barrier including: 30 barriers of asymmetrical W shaped Weir with 0.6 relative distance, a model with 15 barriers with 1.2 relative distance, and 10 barriers with 1.8 relative distance. Based on the obtained results of increasing slope, flow discharge, relative distance, reducing roughness coefficients of barriers height, and dissipation energy dissipation will reduce. The square root of the ratio of 0.87 to 0.65 Darcy Weisbach on the slope 3 percent in the relative distance reaches 1.8. The results of the experiments show that the overflow with a top angle of 40 degrees and the relative distance of 1.2 would be the best conditions for fish crossings in the upstream flow.