Numerical study of the effect of a V‐shaped weir on turbulence characteristics and velocity in V‐weir fishways

Abstract

Fishways are used to allow fish to migrate around water infrastructure, whether movements are in the upstream or downstream direction. Hydrodynamic conditions within various fishways, including turbulence levels, are important for successful fish passage. A numerical hydrodynamic study was conducted for V-weir fishways, which assist species migrating upstream. The variables investigated included, fishway slopes of 4%, 7%, and 10%, relative spacing between weirs of 1.3, 2.6, and 4 (D/L, ratio of distance between weirs to pool width), and weir angles of 22.5 , 40 , and 60 . Turbulence characteristics, including turbulent kinetic energy (TKE), Reynolds shear stress (RSS), turbulent intensity (TI), turbulent dissipation (TD), as well as maximum water velocity, were examined by CFD (computational fluid dynamics) simulation using a re-normalized group or RNG turbulence model. The CFD was calibrated with flow measurements made in a physical model of the V-weir fishway in laboratory control experiments. Based on inferences from fish passage literature, the results showed that, in the range of parameters studied, a weir angle of 22.5 , a slope of 10% and relative spacing between weirs of 1.3 and 2.6 were assessed as offering the best potential performance for several species and sizes of fish, while the latter has lower cost as it requires fewer weirs. The V-weir fishway may be adaptable for smaller fish.

Preferential behavior of Tribolodon hakonensis for fishways according to biological characteristics

“…Several types of fishways have been studied to assist fish in reaching upstream habitats (Helbig et al, 2021; Mensinger et al, 2021; Shahabi et al, 2023). However, no fishway suits all dams and weirs.…”

Debating the Rules: An Experimental Approach to Assess Cyprinid Passage Performance Thresholds in Vertical Slot Fishways

“…In this study, the flow field numerical modelling of the tested fishway configurations was performed with FLOW-3D ® (Santa Fe, NM, USA) [53], a commercial 3D CFD model which has been widely used in recent years for fishway research, e.g., [54][55][56][57][58][59]. FLOW-3D ® uses the Finite Volume Method to solve the governing equations of motion for fluids in a Cartesian staggered grid to obtain transient, three-dimensional solutions to multiscale and multiphysics flow problems [53].…”