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چکیده
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This research investigates how the presence of alternating steps in stepped spillways situated downstream of embankment dams affects the flow properties. This investigation employs Flow 3D software for conducting simulations and analysis. The research goals were achieved by creating six numerical models. These models included two with regular step patterns (MR) and four with alternating step patterns (MA), each varying in terms of step heights and configurations. Each model measured 1.08 m in depth, 2.54 m in length, two regular and two alternatives have 0.6 m width, other two alternative models with 0.9 m width. (MR1, MA1, MA3) have 28 steps with 3.6 cm height, (MR2, MA2, MA4) have 12 steps with 7.2 cm height and 4 steps with 3.6 cm height. All models have a longitudinal slope (θ) of 26.6°. The models were subjected to different flow rates, spanning from 8.01 ≤ Q ≤ 164.3 m3/h, in order to examine and analyze their flow characteristics. To simulate the turbulent flow, the Renormalized group (RNG) turbulence model is done in the numerical modelling. Outcomes indicate that alternative steps cause more energy dissipation than regular steps, and alternatives with 0.9 m width dissipate more energy than alternatives with 0.6 m. by increasing discharge energy dissipation will decrease. And those models which have 7.2 cm step height dissipate more energy than models with 3.6 cm step height. As a results MA4 is a best energy dissipator. Moreover, regular steps have longer hydraulic jump length than alternative steps. and models with alternative steps with 0.9 m width have smaller hydraulic jump than alternative step models with 0.6 m. by decreasing discharge hydraulic jump will decrease. And by increasing the steps height the hydraulic jump will decrease. As a results smaller stilling basin is required for MA4.
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