Numerical Modeling of Hydraulic Properties of Sloped Broad Crested Weir

Document Type : Research Article

Authors

1 Associate Professor, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, East Azerbaijan, Iran.

2 M.Sc. in Civil Engineering-Hydraulic Structures, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, East Azerbaijan, Iran.

3 Ph.D. Student, Department of Civil Engineering, Faculty of Engineering, University of Zanjan, Zanjan, Iran.

4 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.

Abstract

In this study, Numerical modeling of hydraulic properties of sloped broad crested weir is numerically investigated. In order to simulate the free surface flow, the Volume of Flow (VOF) method was used. Turbulence models employed in these simulations were RNG k-ε, and standard k-ε models. The results indicate that RNG k-ε model is more accurate in simulating the flow surface profile of the broad crested weir than the standard k-ε turbulence model. By sloping the crest, the flow depth decreases at the downstream of the weir. At the adverse slope, flow velocity toward the downstream of the crest decrease and flow depth increases. In addition, it was observed that in horizontal or positive slope crests, the control section take place over the crest while for the adverse slope, the control section is slightly shifted toward the upstream of the crest. This could be due to the separation of the flow at the apex of the crest. Moreover, the average Froude number increases for a constant slope (adverse or positive) in the downstream of the weir. It was concluded that the total energy at the downstream of the weir is not a function of the crest slope. The energy increases with the height of the weir and flow discharge. The highest amount of the total energy in downstream of the weir occurs for discharges of 3, 7.4 and 6 lit/s with the slopes of 4:1, 4:-1, 8:-1 and are 0.244, 0.317 and 0.452, respectively.

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