Three-dimensional numerical simulation of flow in vertical slot fishways: validation of the model and characterization of the flow

ABSTRACT Vertical slot fishways allow energy dissipation as a function of the pool, longitudinal slope, baffle and vertical slot design. The mean and turbulent flow patterns in these structures must be compatible with the fish target. The design of these structures is commonly based on previous successful fishways as well as simplified theoretical equations and empirical relationships. To aid in the design of these structures, a three-dimensional hydrodynamic model was used to simulate the flow, and experimental studies were used to validate the model. The mean velocities, pressures and parameters indicative of turbulence were analyzed. The maximum flow velocities were up to 32% higher than the values obtained using a simplified theoretical equation. The evaluation of the volumetric dissipated power indicated that the mean value for the pool was lower than 150 W/m3; however, analysis of the spatial distribution showed that in some areas, the values can exceed 1000 W/m3. The results indicate that the numerical simulation was able to adequately represent the flow considering the computational cost involved. Accordingly, it can be used as a complementary tool for the design of new fishways and for the analysis of modifications in existing ones.