Optimizing discharge efficiency of trapezoidal labyrinth weirs

ABSTRACT This study uses 3D numerical modeling to analyze the hydraulic performance of trapezoidal labyrinth weirs, focusing on geometric parameters like relative apex length (Ln/Bc), weir height (P), and stepped crests and their effect on the discharge coefficient (Cd). Simulations revealed that shorter apex lengths (Ln/Bc = 0.26) reduce flow recirculation, boosting Cd by up to 30% compared to longer design (Ln/Bc = 0.93). An inverse relationship was found between weir height and Cd, with peak efficiency at lower relative heads (h/P = 0.5). Discontinuous stepped crests enhanced flow separation and reduced vorticity, improving Cd over the baseline model. A regression model was developed to predict Cd based on h/P, Ln/Bc, and P/Bc, achieving a 4.2% mean error. This study contributes to the optimization of trapezoidal labyrinth weir design by quantifying the effects of geometric compactness and stepped crests, offering practical insights for optimizing flood management structures.