Author(s): Cumhur Ozbey; Serhat Kucukali

Linked Author(s): Serhat Kucukali

Keywords: Fish-friendly fine screen; Numerical modeling; Porous media approach; Turbulence models; Flow field

Abstract: The present study focuses on a specific type of physical barrier, the fish-friendly Oppermann fine screen, that can be used at the water intakes of various hydropower plants. The screen profile is designed with vertical hydrodynamic bars having a rounded leading edge and a smooth bar surface, thus enhancing the hydraulic conditions in the vicinity of the screen. The Oppermann fine screen is numerically investigated in a Computational Fluid Dynamics (CFD) model, where the analyses comprise the investigation of the flow field and turbulent quantities around the screen. In this regard, flow through the Oppermann fine screen was numerically modeled by using a porous media approach, and the numerical results were compared with the experimental data. Four different turbulence models, namely the k-ε standard, k-ε RNG, k-ω, and Large Eddy Simulation (LES) were tested. To find the best turbulence model, mean absolute percentage errors (MAPE) between the physical and numerical model results for the time-averaged values of the instantaneous streamwise velocities were considered. The LES model is shown to yield a lower MAE value of 7.6% compared to RANS turbulence models. Moreover, the required number of mesh cells to construct the numerical model with the porous media approach is found to be significantly reduced resulting in saving computational cost substantially. Additionally, numerical outcomes have also shown that the hydrodynamic bar profile of the Oppermann screen dampened the macro-turbulence leading to a more homogeneous and symmetrical downstream flow field.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0241-cd

Year: 2023