Industrial Innovations

Industrial Innovations

Numerical Simulation of Secondary Bottom Outlet of RUDBAR Dam in Lorestan to evaluate the Jet Length and Cavitation Risk

Document Type : Original Article

Authors
Maryam Gharibipour 1
Mohsen Nasrabadi 2
Hamed Safikhani 1
Younes Aminpour 3
1 Department of Mechanical Engineering, Faculty of Engineering and Technology, Arak University, Arak, Iran.
2 Department of Water Science and Engineering, Faculty of Agriculture and Environment, Arak University, Arak, Iran.
3 Hydraulic Structures Department, Water Research Institute, Ministry of Energy, Tehran, Iran.
10.618826/jii.4.1.1
Abstract
In this research, the flow behavior in the secondary bottom outlet of the Roudbar- Lorestan Dam was numerically analyzed using ANSYS CFX software, with an emphasis on predicting the length of the issuing jet and the possibility of cavitation occurrence. For validation, the outputs of the numerical model were compared with experimental results obtained from the dam’s reduced-scale physical model (1:20). The meshing process and grid independence study showed that using cubic elements with approximately 900,000 elements could reduce the error in the issuing jet length to less than 8%. After evaluating various turbulence models, the K−ω model was selected as the superior turbulence model with a mean relative error of 7.88%. Furthermore, the results indicated that at the maximum flow rate, the simulated jet length was predicted to be about 22% shorter than the initial design state. Analysis of local pressures and the cavitation index also showed that in the high-velocity flow regions and near the gate, the cavitation index reached a minimum value of 0.78, which is close to the threshold for the occurrence of cavitation. In contrast, the values of this coefficient in the middle and end sections of the jet were higher than 1.2, and the probability of cavitation in these areas was assessed as very negligible. Overall, the findings of this research demonstrate that numerical simulation can be used with high accuracy, exceeding 95%, in predicting the jet length and evaluating cavitation conditions, and is considered an efficient tool for the analysis and optimization of the design of dam bottom outlet.
Keywords
Bottom Outlet
Numerical Simulation
Rudbar-Lorestan Dam
Cavitation
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Industrial Innovations
Volume 4, Issue 1 - Serial Number 13
In Press
Winter 2026
Pages 1-20

  • Receive Date 20 November 2025
  • Revise Date 05 December 2025
  • Accept Date 17 December 2025