Reach Professional-Grade ANSYS Fluent Training Course — Ep 03
Free Surface Flow: Lifting Dam
- Lesson
- 03
- Run Time
- 17m 36s
- Published
- Jun 25, 2026
- Category
- ANSYS Fluent
- Course Progress
- 0%
Lifting Dam (Dam Break) — ANSYS Fluent CFD Simulation Training
This project presents a numerical simulation of a lifting dam (dam break) using ANSYS Fluent. The VOF (Volume of Fluid) model is used to capture the two fluid phases, with the goal of studying how the free surface of the fluid evolves over time. Two cases are examined: in the first, the flow continues freely after the dam is lifted, while in the second, it encounters an obstacle in its path.
Geometry & Mesh
The two-dimensional geometry was created in SpaceClaim, with a computational domain measuring 70 mm in length and 40 mm in height.
Meshing was performed in ANSYS Meshing using an unstructured grid throughout. Case 1 contains 86,611 elements, while Case 2 contains 132,614 elements.
Methodology
Several assumptions underpin the model. Because the flow is incompressible, a pressure-based solver is selected, and the simulation is run as transient. Gravity is applied at −9.81 m/s² along the Y-axis. The two phases — air (density 1.225 kg/m³, viscosity 1.7894e-05 kg/m·s) and liquid water (density 998.2 kg/m³, viscosity 0.001003 kg/m·s) — are modeled with the Volume of Fluid approach using an explicit, sharp-interface formulation and implicit body forces.
The laminar viscous model is used to solve the flow-field equations, with the SIMPLE scheme for pressure–velocity coupling. Momentum is discretized using second-order upwind, while pressure uses the PRESTO! scheme. The solution is initialized with the standard method, after which the water phase is patched into the initial region (volume fraction = 1). The calculation runs with adaptive time advancement over 2000 time steps at a step size of 0.0005 s.
Results
The simulation tracks the free surface of the fluid as the dam is lifted. Once the solution is complete, contours of velocity, pressure, and volume fraction are extracted. In the second case, after the flow strikes the barrier it rises to a relatively high level, driven by the high kinetic energy present in the initial moments of the flow.