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.