Abstract
Hydrofoil-crested weirs (HFWs) are increasingly applied in hydraulic systems due to their ability to regulate flow and dissipate energy efficiently, yet their hydrodynamic behavior remains strongly dependent on crest geometry. However, the influence of hydrofoil thickness on critical hydraulic parameters like flow velocity, pressure, and turbulence has not been comprehensively quantified. This study presents a numerical investigation of flow over HFWs with different hydrofoil thickness ratios, focusing on the distributions of velocity, pressure, and turbulence-related parameters under various discharges. Simulations were performed using a Reynolds-averaged Navier–Stokes (RANS) framework, employing a high-fidelity CFD approach with turbulence models to capture key hydraulic characteristics. Results were analyzed at multiple downstream stations to assess the influence of geometry on flow structures, with particular attention to the quantitative effects of hydrofoil thickness on flow dynamics. The findings quantitatively demonstrate that hydrofoil thickness substantially affects near-crest velocity and turbulence fields. Thicker profiles resulted in up to a 20% increase in near-surface jet velocity and produced 30–40% higher turbulent kinetic energy compared to thinner profiles. Thicker profiles promote earlier acceleration of the surface jet and produce wider high-velocity zones in the upper water column, while maximum velocities further downstream converge across geometries. Pressure analysis revealed that thicker crests generate stronger local loadings and sharper reductions in pressure immediately downstream of the crest, with inter-geometry differences up to ~ 15% under identical flow conditions. However, pressure distributions stabilize toward near-hydrostatic profiles at distances beyond ~ 0.3–0.5 m downstream. However, pressure distributions stabilize toward hydrostatic profiles at greater distances. Turbulence characteristics exhibited the strongest dependence on hydrofoil geometry, with thicker profiles (N36) producing significantly higher turbulent kinetic energy (TKE), turbulence intensity (TI), and dissipation rates (TD), particularly in the surface and mid-depth regions. Compared with thinner profiles, these enhancements promote stronger vertical mixing and energy dissipation, with differences reaching up to ~ 35%. Overall, the results highlight a trade-off between stability and dissipation efficiency: thinner crests provide smoother velocity and pressure fields, whereas thicker crests enhance turbulence-driven energy dissipation. These insights support the selection and optimization of HFW designs for diverse hydraulic applications.