Analysis of hydraulic performance and energy dissipation efficiency in three-stage stilling basins with different groove geometries

ABSTRACT This study systematically compared groove geometries (semi-circular, V-shaped, trapezoidal) in three-stage stilling basins operating under low-Froude-number (Fr < 1) submerged hydraulic jumps. Semi-circular grooves achieved 55.6% energy dissipation efficiency-surpassing smooth basins by 30.2% and outperforming V-shaped/trapezoidal designs by 12.8/52.3%. Centrifugal effects generated high-intensity secondary vortices with 23–37% stronger vorticity transport, which amplified turbulent kinetic energy dissipation while reducing pressure fluctuation amplitudes at tailing weirs by 18–25%. The first two stages contributed 68 – 73% of total dissipation. These findings, validated through RNG k-epsilon modeling and experiments, establish semi-circular grooves as an optimal solution that enhances hydraulic performance and structural stability in low-Fr regimes.