Modelling void fraction distributions in breaking hydraulic jumps

Hong Hu, Hang Wang, Matthias Kramer

We present two models for predicting void-fraction distributions in hydraulic jumps, addressing the limitations of the conventional two-layer formulation in representing continuous profiles. The first model introduces a two-state convolution to describe the smooth transition between the turbulent shear and roller regions, while the second applies a superposition framework to capture the overlapping contributions from both layers. Validation against experimental data shows that both models improve the representation of the transition region and provide a more realistic connection between the upper and lower aerated layers. The proposed formulations not only reproduce measured profiles more accurately but also provide a continuous and physically consistent description across the entire flow depth. These models offer a practical tool for hydraulic design and advance the understanding of vertical mass transport in highly aerated flows.