Numerical analysis for Orifice Spillway with and without Super Elevation

Orifice spillways serve a dual function: managing floods and effectively clearing sediments through flushing mechanisms. In instances where a spillway is situated within a confined valley, it's noted that the water jets discharged from the orifice often collide with either the left or right riverbank, resulting in erosion or damage to that particular area. To prevent this, training walls are often provided. Alternatively, spillway buckets are provided with deflectors to deflect the flow to a desired location. However, in scenarios where the necessary deflection surpasses the capacity of deflectors, a spillway profile is provided with super elevation to effectively manage the flow. By providing super elevation, the spillway's outer edges are raised or inclined higher than the inner edges. This design creates a sloped or curved surface for the water to flow smoothly, reducing the impact of centrifugal forces. It helps distribute the force of the flowing water more evenly along the spillway, minimizing the risk of damage and ensuring the safe discharge of excess water from reservoirs or dams. In this paper, the computational fluid dynamics (CFD) program FLOW 3D is used to analyze the behavior of orifice spillway and flow distribution with and without super elevation. Studies were carried out for four different conditions: (1) orifice spillway without super elevation; (2) orifice spillway with super elevation solely on the Right span; (3) orifice spillway with super elevation solely on the left span; and (4) orifice spillway with super elevation on both extreme right and left spans. The hydraulic characteristics of orifice spillways such as the water surface, discharge, and vertical pressure distribution along the spillway profile, were obtained from the CFD analysis. Subsequently, a comparative study was conducted based on these results. The results of this study will offer essential technical insights into the flow distribution patterns when super elevation is applied to specific spans of an orifice spillway.