Flow characteristics of bottom outlets with moving gates

Abstract

This study investigates the discharge characteristics of a bottom outlet with a moving gate by Flow3D. Experimental results for a scale model outlet of the Aswan Dam, Egypt, were used. Two different flow features were found. Pressurized flow established if the flume was filled and then the gate was slowly opened. However, a free surface flow occurred if the gate was fully opened and the entire flume was slowly flooded with water. The numerical simulations successfully captured the two flow patterns as well as the discharges and water surface profiles. The discharges were predicted with sufficient accuracy using the first-order momentum advection scheme. In comparison with the k-ϵ turbulence model, the Re-Normalization Group model yields the best agreement with the experiments. The model performed with similar accuracy for both model and prototype cases.

Keywords:

• Bottom outlet
• CFD simulation
• moving gate
• three-dimensional model
• VOF model

Acknowledgements

The research was sponsored by the Swedish Hydropower Centre (SVC). The licence to use Flow3D was issued by Flow Science Inc., Santa Fe, NM, USA. The investigator has also benefited from useful suggestions made by the Flow3D support group, especially by Melissa Carter.

Additional information

Notes on contributors

Bijan Dargahi

IAHR Member