Model development in OpenFOAM to predict spillway jet regimes

Abstract

Hydropower is the most important renewable energy source. Though hydropower provides abundant benefits, dams have also altered natural flow conditions affecting fish habitat. Elevated total dissolved gas (TDG) can result in gas bubble disease in affected fish. TDG production depends on the gas volume fraction and bubble depth in the tailrace, which are a function of spillway jet regimes. This paper presents a model developed in OpenFOAM to predict spillway jet regimes. The model utilizes the volume of fluid method to capture the dynamic free surface. A Large Eddy Simulation model, together with Detached Eddy Simulation, was used for turbulence closure. The model adequately reproduced jet regimes observed in a reduced-scale laboratory model. Differences in jet regimes predicted at reduced and prototype scales were observed. Results suggest that turbulence, not scaled in the laboratory model, plays an important role in the flow characteristics downstream of spillways.

Keywords:

• dams
• numerical simulations
• environmental fluid mechanics
• environmental hydraulics
• CFD
• OpenFOAM
• hydropower

Acknowledgements

The authors gratefully acknowledge the Hydro Research Foundation for the support of this research project.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

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Notes on contributors

Yushi Wang graduated in environmental sciences from the Florida F&M University (2007), and holds a Ph.D. in Civil and Environmental Engineering from the University of Iowa (2013). His areas of expertise include numerical simulation of hydrodynamic, water quality modeling, hydraulic design and environmental impact assessment.

Marcela Politano is a Research Engineer at IIHR – Hydroscience & Engineering, The University of Iowa. She holds a Ph.D. from Instituto Balseiro, Argentina. Her background includes modeling of multiphase flows, total dissolved gas, and heat and mass transfer. She has expertise in numerical modeling of the hydrodynamics and water quality in rivers, tailraces, reservoirs and fish passage facilities. During the past 10 years, she has supervised over 30 projects for the power industry in USA.

Ryan Laughery is a hydraulic engineer for the Walla Walla District Corps of Engineers. He obtained his bachelor's degree in civil engineering from Washington State University in 2002. From 2002 until now, he has primarily been involved in the design and development of fish passage structures for Lower Columbia and Lower Snake River hydropower projects. For the past several years, he has served as technical lead for the development of physical and numerical models for the evaluation of configurations and operations of hydropower projects to improve fish survival.

Larry Weber is Professor of Civil & Environmental Engineering, the Edwin B. Green Chair in Hydraulics, and Director of IIHR – Hydroscience & Engineering. He is co-founder of the Iowa Flood Center and was instrumental in the establishment of the Iowa Nutrient Center. His research expertise includes fish passage facilities, physical modeling, river hydraulics, hydropower, computational hydraulics and ice mechanics. Most of his current research activities focus on the measurement and computational modeling of water quantity (i.e. flooding) and quality (sediments and fate and transport of nutrients) at the watershed scale.