Approach to the Void Fraction Distribution within a Hydraulic Jump in a Typified USBR II Stilling Basin

This research constitutes a first approach to analyze the void fraction distribution in a hydraulic jump taking place within a typified USBR II stilling basin. In order to carry out this task both, a physical and a numerical Computational Fluid Dynamics (CFD) model of the case study have been developed. Measurements of the void fraction have been taken in different profiles throughout the hydraulic jump for both models and then, a comparison of the results obtained has been made, taking also into account data from other authors regarding void fraction distribution in classical hydraulic jumps. The results of this comparison show that the physical model, in which an optical fibre probe has been used for the experimental campaign, is able to completely reproduce the aeration of the hydraulic jump, whereas the numerical model misses to simulate certain aeration mechanisms. The models developed also provide information on how the energy dissipation devices from the USBR II stilling basin affect the void fraction distribution within the jump, which in turn can be useful for the adaptation of dams to higher discharges than those considered in their design.