Technical fish passes are key hydraulic structures ensuring longitudinal river connectivity disrupted by weirs and dams, allowing natural fish migration. This study presents a detailed numerical analysis of the hydraulic behavior of pool-type fishways designed for rheophilic species in mountain areas, particularly Salmo trutta fario (brown trout). The analysis was performed using three-dimensional Computational Fluid Dynamics (CFD) modeling based on the finite volume method and the Reynolds-Averaged Navier–Stokes (RANS) equations coupled with the standard k–ε turbulence model. Four geometric configurations were analyzed, differing in baffle number, spacing, and slot geometry. Results showed significant variations in velocity fields (0.65–1.35 m/s), indicating that fishways with three baffle rows and narrow longitudinal slots provided stable flow conditions compatible with trout swimming capacity. Configurations with larger baffles generated high turbulence and unfavorable local velocities. The study highlights the value of CFD modeling as a design tool for species-specific optimization of technical fishways. Future research will extend the analysis to sedentary species such as Cottus gobio and integrate bioenergetic and behavioral models to assess hydraulic performance under varying flow conditions.
Ianculescu et al. (2025) studied this question.