Integrating Numerical Modelling with Image-Based Experimental Approaches on a Highly Turbulent Breaking Bore

Abstract This study presents a novel approach integrating large-scale physical experiments with advanced numerical modelling to investigate the complex dynamics of a highly turbulent breaking bore with a Froude number of 2.4. Physical experiments were conducted in a 19-m flume using ultra-high-speed cameras and acoustic displacement metres to capture free-surface profiles and air–water interactions. Concurrently, a two-dimensional large eddy simulation (LES) model was developed in OpenFOAM using the InterFoam solver and Smagorinsky subgrid scale turbulence closure. The model successfully replicated the bore generation and propagation processes, including air entrainment mechanisms and large-scale vortex structures. Validation against experimental data showed strong agreement in free-surface profiles, velocity fields, and void fraction distributions. The study revealed that early-stage air entrainment was driven by clockwise vortices from incoming flow, whilst fully developed bore propagation was dominated by counterclockwise roller toe vortices. Despite limitations in resolving fine-scale bubble breakup due to mesh constraints, the LES model effectively captured the dominant turbulent structures. The findings underscore the potential of combining image-based techniques with CFD to enhance understanding of transient, aerated flows in extreme hydrodynamic events. Future work will focus on refining mesh resolution to simulate bubble-scale turbulence more accurately.