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Numerical Simulation of Two-Phase Flow over Mandali Dam Ogee Spillway

Riyadh Zuhair Al Zubaidy and Shaymaa Abdul Muttaleb Hashim Alhashimi
Water Recourses Engineering Department, College of Engineering, University of Baghdad, Iraq
Highway Engineering Department, College of Engineering, University of Al- Mustansiriya, Iraq

Abstract—Spillway flows are essentially rapidly varying flows near the crest with pronounced curvature of the streamlines in the vertical direction. Spillway hydrodynamics can be obtained through physical modeling or numerical modeling. Physical modeling of spillways is expensive, time-consuming and many difficulties associated with scaling effects and measurement devices. Nowadays, using computational fluid dynamic (CFD) codes, flow behavior in the hydraulic structures can be investigated in reasonable time and expense. Due to the complexity of air-water two-phase flow over ogee spillways, a numerical study of the free surface flow on an ogee-crested is presented. A numerical model which solves the RANS equations coupled to a surface-capturing algorithm to predict the flow in air and water was developed using the finite volume module of the FLUENT software. Two types of multiphase flow models are used: a mixture multiphase flow model (MMF) and a volume of fluid model (VOF). The differences between both models are the phases interpenetrating and the phase velocities. In both models, the RNG k-ε model is chosen to simulate turbulence with the PISO arithmetic technique. The free surface numerical model is applied on a Mandali Damogee spillway as a case study to investigate the hydraulic characteristics of flow over spillway crest profiles by predicting the velocity distribution, pressure distribution and discharge characteristics..Results from several runs of software compared with corresponding experimental data. It is shown that there is a close agreement for the discharge capacity over the spillway between physical model and FLUENT predictions. The data series obtained for model comparison include; velocity profiles, pressure distribution, and characteristics of flow. Both models can satisfactorily simulate the flow pattern and the recirculation regions. The velocity profiles are more accurately simulated using the VOF model than MMF model. 
Index Terms—ogee spillway, finite volume method, CFD modeling, fluent software, flow velocity, discharge capacity

Cite: Riyadh Zuhair Al Zubaidy and Shaymaa Abdul Muttaleb Hashim Alhashimi, "Numerical Simulation of Two-Phase Flow over Mandali Dam Ogee Spillway," International Journal of Structural and Civil Engineering Research, Vol. 2, No. 3, pp. 1-13, August 2013.