Hydrodynamic optimization of bilateral-symmetric multi-slot fishway using computational fluid dynamics

This study compares the hydrodynamic characteristics of the vertical-slot fishway (VSF), the original bilateral-symmetric multi-slot fishway (BMSF-8) and 12 modified bilateral-symmetric multi-slot fishways (BMSF-R1–BMSF-R12). Numerical results indicate that BMSF-R11 has the best hydrodynamic performance among all the fishways considered. For instance, the maximum time-averaged velocity is 2.03–2.08 m s−1 in VSF, 1.36–1.45 m s−1 in BMSF-8, and 1.13–1.15 m s−1 in BMSF-R11. The maximum time-averaged turbulent kinetic energy is 0.186–0.214 m2 s−2 in VSF, 0.109–0.141 m2 s−2 in BMSF-8, and 0.073–0.083 m2 s−2 in BMSF-R11. The region with the time-averaged velocity less than 1.00 m s−1 accounts for 71.9–72.3% in VSF, 77.7–81.5% in BMSF-8, and 90.1–92.1% in BMSF-R11. The region with the time-averaged turbulent kinetic energy less than 0.05 m2 s−2 accounts for 60.3–64.8% in VSF, 63.5–77.2% in BMSF-8, and 97.0–97.9% in BMSF-R11. Consequently, BMSF-R11 serves as a better multi-species fishway for fishes with different swimming abilities, but fish-passage tests with live fish should be performed to verify this declaration in the future study.