Hydraulic Jump and Flow Energy Dissipation Downstream Cylindrical Stepped Weir

Hydraulic jumps are critical phenomena in hydraulic engineering, observed in open channels, rivers, and coastal areas. This study investigates the characteristics of hydraulic jumps formed downstream of stepped cylindrical weirs. A total of 27 physical models of stepped cylindrical weirs were constructed, varying weir heights (P = 30, 45 and 60) cm, three step sizes (D = 2.5, 5, and 7.5 cm), and a fixed downward slope of the weir (θ = 45°). Three step configurations were tested: (Fc) circular steps (no cuts), (Fc & Hc) a combination of circular and half-cut steps, and (Hc) half-cut steps. The results show that energy loss increases with higher weir heights, higher Froude numbers upstream of the hydraulic jump, and greater ratios of downstream to upstream water depths. Additionally, energy dissipation decreases with smaller step diameters and lower discharge rates. Among the step configurations, the circular steps (Fc) yielded the lowest energy dissipation, outperforming the half-cut configurations (Fc & Hc and Hc). These findings provide valuable insights for optimizing the design of stepped cylindrical weirs in open channel flows.