Babak Sanahmadi - Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran.
Majeid Heydari - Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran.
Saeed Gohari - Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamadan, Iran.
Saeid Shabanlou - Department of Water Engineering, Faculty of Agriculture, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran.

In this paper, the flow in the vicinity of rectangular side orifices placed in main channels is estimated by means of the FLOW-۳D model. To reconstruct the flow free surface, the volume of fluid (VOF) approach is utilized. In addition, the standard k-ε and RNG k-ε turbulence models are employed to predict turbulence flow. According to the results obtained from the numerical modeling, the RNG k-ε turbulence model has higher accuracy than the standard k-ε. The analysis of the numerical modeling results proved that this model forecasts the discharge coefficient of side weirs with suitable accuracy. On the other hand, the mean absolute percent error (MAPE) is calculated equal to ۱۲.۲۰۴%. Also, the maximum pressure is simulated near the main channel bed. Moreover, the minimum pressure is estimated near the flow free surface. Regarding the numerical simulations, the maximum turbulence energy state occurs near the inlet of the side orifice and by increasing the side orifice dimensions the flow field turbulence energy value increases.

FLOW-۳D, Flow pattern, k-ε turbulence model, Numerical Simulation, Rectangular side orifices