Ogee Spillway

Ogee Spillway CFD Simulation, ANSYS Fluent Training

Description

The primary function of a spillway is to safely discharge excess water during high-flow events such as floods, protecting the dam body from damage caused by overtopping or excessive pressure. Spillways typically consist of a vertical plate oriented in the direction of flow, with an upper edge that may be sharp-crested, curved, or wide, depending on the design. Common spillway types include open channel, chute, stepped, siphon, ogee, side channel, and labyrinth configurations.

This project simulates an ogee spillway using ANSYS Fluent, investigating the behavior of water flow after passing over the spillway crest in the presence of surrounding airflow.

The geometry was designed in Design Modeler, modeled as a horizontal cylinder with a horizontal inlet for the mixture flow and two vertical outlets for the separated gas and liquid streams. The domain was meshed in ANSYS Meshing using an unstructured mesh totaling 10,959 cells.

Methodology

Since the channel involves two distinct fluid phases, a two-phase flow model was applied using the VOF (Volume of Fluid) approach, with water defined as the primary phase and air as the secondary phase. Because the boundary between the two phases is sharply defined, the sharp interface modeling option was used to accurately capture the behavior at the water-air boundary.

Conclusion

Post-processed results include contours of velocity, pressure, and the mass fraction of water and air. The results show water striking the dam body and beginning to overflow at the spillway's upper edge. The excess flow then slides down the spillway's curved slope at reduced pressure, helping to dissipate the incoming flow's energy and preventing floodwaters from intensifying further downstream.