University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 52 5 2021 07 23 Numerical Simulation of Energy Dissipation in Crescent-Shaped Contraction of the Flow Path Numerical Simulation of Energy Dissipation in Crescent-Shaped Contraction of the Flow Path 1299 1314 82365 10.22059/ijswr.2021.318989.668895 FA Rasoul Daneshfaraz Professor, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Iran. 0000-0003-1012-8342 Ehsan Aminvash M.sc student, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Iran. 0000-0001-8901-2232 Hamidreza Abbaszadeh M.sc student, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Iran 0000-0001-7714-6081 Journal Article 2021 02 13 One of the methods of controlling and reducing flow energy is to use energy dissipating structures through formation of hydraulic jumps. One of these types of structures is the constriction elements in the flow path, which leads to a decrease in the energy of the passing flow. In the present study, the effect of crescent-shaped contraction as an energy dissipating structure in the supercritical flow path has been investigated using FLOW-3D software. Examining the simulation results, the RNG model among the four turbulence models, RNG, k-ε, k-ω and LES was selected due to its higher accuracy and lower relative error and absolute error percentage. In this study, the amplitude of the Froude number after the gate as the most effective dimensionless parameter in energy dissipation varied from 2.8 to 7.5 and the values of stenosis on both sides are 5 and 7.5 cm. The results show that in all cases of using the crescent-shaped contractions, the energy dissapation in 5 and 7.5 cm contractions are respectively 24.62% and 29.84% more than the ones in the classic free jump, based on the energy drop relative to the upstream, and 46.14% and 48.42% more, based on the energy drop relative to the downstream. Also, by reviewing the previous researchs, it was found that the crescent-shaped contractions have a better performance in terms of energy loss compared to the sudden contraction. Based on the simulation results, with increasing the upstream Froude number, the energy dissipation is increased relative to the upstream and downstream of crescent-shaped contraction, so that the use of contraction elements reduces the downstream Froude number of the contracted section in the range of 1.6 to 3/2. One of the methods of controlling and reducing flow energy is to use energy dissipating structures through formation of hydraulic jumps. One of these types of structures is the constriction elements in the flow path, which leads to a decrease in the energy of the passing flow. In the present study, the effect of crescent-shaped contraction as an energy dissipating structure in the supercritical flow path has been investigated using FLOW-3D software. Examining the simulation results, the RNG model among the four turbulence models, RNG, k-ε, k-ω and LES was selected due to its higher accuracy and lower relative error and absolute error percentage. In this study, the amplitude of the Froude number after the gate as the most effective dimensionless parameter in energy dissipation varied from 2.8 to 7.5 and the values of stenosis on both sides are 5 and 7.5 cm. The results show that in all cases of using the crescent-shaped contractions, the energy dissapation in 5 and 7.5 cm contractions are respectively 24.62% and 29.84% more than the ones in the classic free jump, based on the energy drop relative to the upstream, and 46.14% and 48.42% more, based on the energy drop relative to the downstream. Also, by reviewing the previous researchs, it was found that the crescent-shaped contractions have a better performance in terms of energy loss compared to the sudden contraction. Based on the simulation results, with increasing the upstream Froude number, the energy dissipation is increased relative to the upstream and downstream of crescent-shaped contraction, so that the use of contraction elements reduces the downstream Froude number of the contracted section in the range of 1.6 to 3/2. https://ijswr.ut.ac.ir/article_82365_a2c3ba71f3c17e43a051bd2e7da7e506.pdf