Abstract
This study examines the complex three-dimensional (3D) air-water flow characteristics in a chute spillway using Ansys Fluent for numerical simulations. The Volume of Fluid method incorporating a dispersed interface and Large-Eddy Simulation was evaluated along with the Renormalization Group
k-ε
model for comparative analysis. Based on available experimental data, the numerical model was validated using two structured grids: Uniform Structured Mesh (USM) and Locally Refined Structured Mesh (LRSM). The approach velocity was
v
= 6.831 m/s, corresponding to a Froude number of 7.525 and a Reynolds number of 1.313 × 10
6
, measured upstream of the aerator. The analysis was conducted in two stages: (i) an assessment of mesh refinement and (ii) an evaluation of LES sub-grid-scale (SGS) models. The numerical results demonstrate that both procedures reproduce the general trends of flow pattern, jet length, velocity, and pressure along the chute. However, pronounced differences arise in the prediction of air concentration within the cavity and reattachment zone. Among the investigated approaches, the Locally Refined Structured Mesh coupled with SGS models provides better agreement with experimental results, capturing flow patterns, pressure distribution, air concentration in the cavity, and the downstream region with reasonable accuracy. The Uniform Structured Mesh and RNG
k-ε
exhibit larger deviations in terms of flow pattern, velocity, pressure, and air concentration. The findings demonstrate that aerated spillway flow predictions are more sensitive to grid resolution than to SGS modelling configurations.