Hydraulic characteristics and energy dissipation of different reverse arc surface step spillways: a comparative study

ABSTRACT Step spillways offer significant advantages in hydraulic performance and energy dissipation. To explore these aspects in reverse arc surface step spillways, three spillway designs with varying curvatures were developed based on practical engineering considerations. Using the RNG model, a comparative analysis was conducted on flow patterns, velocity distribution, turbulent kinetic energy dissipation, head variations, Froude number changes, energy dissipation rates, and pressure distribution among the three spillway models. The results indicate that the location of the reverse arc point significantly influences the position of the water tongue and the cavity size. As the reverse arc point shifts downstream, turbulent dissipation increases. Among the models, the FH2 design exhibited the highest energy dissipation, while the FH1 design demonstrated the lowest. The pressure distribution across the spillway steps was similarly affected by the reverse arc point's position; as this point moved outward, the pressure on the outer step face increased while the cavity size reduced. The FH2 model achieved the highest energy dissipation rate (50.77%), indicating superior energy dissipation performance, followed by the FH3 model (42.49%), with the FH1 model having the lowest performance (32.67%). These findings provide valuable theoretical insights for the design, optimization, and engineering applications of spillways.