Numerical Study of Turbulent Characteristics and Aeration Patterns in Breaking Surge Waves

Positive breaking surge waves are caused by a sudden change in flow. 3D numerical simulation provides a holistic approach to simulate the turbulent behaviour behind a breaking surge wave. A combination of Volume of Fluid (VOF) method and Large Eddy Simulation (LES) is utilized for Froude numbers ranging from 1.71 to 2.49. Computational mesh is refined sufficiently to improve the LES quality by resolving at least 90% of the total Turbulent Kinetic Energy (TKE). At surge toe, strong aeration and surface perturbation are observed caused by intense TKE in the area. Velocity perturbations show positive turbulent production in xy-plane rather than yz-plane as the shear instability exists in xy-plane. Finally, the vortices start from a 1D structure at the toe and exhibit rod shape upstream in anisotropy maps. This study highlights the role of instability mechanisms in the formation of a breaking surge wave.