Free Surface Flow: Spillway, Transient Solver

This project simulates the two-phase flow of water and air over an ogee spillway — the curved overflow structure used in dams to pass excess water safely downstream. When flow meets an obstruction, the water level rises behind it and accelerates over the crest; an ogee profile is shaped specifically to match the natural nappe of falling water, minimizing pressure problems and maximizing discharge efficiency. Capturing the free water surface as it spills over the crest is the core of the problem and a classic application of free-surface CFD in civil and hydraulic engineering.

The physics is handled with the Volume of Fluid (VOF) multiphase model, which tracks the sharp air–water interface as it deforms over the spillway, with standard k-ε closing the turbulence. Because the whole point is to watch the water move, accelerate, and form its surface profile over the crest, the case is solved transient.

Setup: water enters the computational domain at a mass flow rate of 0.05 kg/s and flows over the spillway against the air phase. Geometry is built in ANSYS Design Modeler and meshed in ANSYS Meshing with a structured mesh (12,846 elements) — structured here because the spillway's smooth, well-defined geometry suits a clean, aligned grid along the flow path.

What the results show: contours of pressure, velocity, and phase volume fraction extracted across the domain, revealing the water surface profile over the crest, the acceleration of the flow down the spillway face, and the pressure distribution along the structure — exactly the quantities a hydraulic engineer uses to assess discharge capacity and surface pressures.

Included: Geometry & Mesh file, plus a comprehensive training movie walking through the full setup, solution, and extraction of all results.

You'll learn to: set up a transient VOF air–water free-surface case, define mass-flow inflow over a curved spillway, apply standard k-ε turbulence, and read the free-surface profile and pressure field from volume-fraction and pressure contours.