Sharpen Your ANSYS Fluent Skills to Expert Level — Ep 02
Agricultural & Food: Spillway, Transient Solver
- Lesson
- 02
- Run Time
- 21m 19s
- Published
- Jul 9, 2026
- Category
- Aerodynamics & Aerospace
- Course Progress
- 0%
Spillway CFD Simulation
Description
In this project, a three-dimensional spillway is simulated using ANSYS Fluent to study how excess water is managed and released from a dam structure. Spillways serve as the outlet mechanism for a dam, designed to safely carry surplus water and floodwater from the reservoir side down to the downstream side once the water level rises past a defined threshold. Because agricultural water management relies heavily on dams and reservoirs for irrigation supply, understanding spillway hydraulics is directly relevant to agricultural and food engineering applications, where controlled water release protects both the structure and the farmland downstream.
Several spillway designs exist, including ogee-shaped, stepped, side-channel, lotus, tunnel, and siphon spillways. This project focuses on simulating the flow behavior over one such spillway geometry using a multiphase approach, treating air as the primary phase and water as the secondary phase. In the model setup, the water column at the inlet reaches a height of 0.155 m, while the full model height is 0.306 m, and the dam structure itself has a height of 0.156 m.
The three-dimensional geometry was built in Design Modeler, and the mesh was generated in ANSYS Meshing using an unstructured mesh strategy, resulting in a total of 698,691 elements.
Methodology
The two-phase air-water interaction is captured using the Volume of Fluid (VOF) multiphase model. Gravity is applied along the y-axis at a magnitude of -9.81 m/s² to correctly represent the driving force behind the water's downward flow over the spillway.
Conclusion
The resulting flow contours confirm that the spillway performs as intended, allowing the water to pass over the structure smoothly. The highest flow velocities appear where the flow cross-section narrows, since the water accelerates as it's forced through the tighter geometry — a behavior consistent with what's expected in real spillway operation and useful for engineers designing water release systems for agricultural reservoirs.