# Turbulence and self-similarity in highly-aerated shear flows: the stable hydraulic jump

## TL;DR

This study investigates turbulence and self-similarity in a stable hydraulic jump with high air entrainment, providing detailed turbulence measurements and spectral analysis to aid numerical modeling of complex air-water flows.

## Contribution

It introduces novel intrusive phase-detection and image-based velocimetry techniques to analyze turbulence in hydraulic jumps, advancing understanding of air-water flow dynamics.

## Key findings

- Velocity spectra follow a -5/3 slope in the inertial subrange.
- Energy transfer occurs from inertial range to bubble-related frequencies.
- Data supports high-fidelity numerical model validation.

## Abstract

Hydraulic jumps are oftentimes encountered in natural and human-made environments. The transition from supercritical to subcritical flow involves large energy dissipation rates and substantial air entrainment, preventing the use of monophasic flow measurement instrumentation. This paper presents an experimental study of a stable hydraulic jump with a Froude number of 4.25, utilizing novel intrusive phase-detection probe techniques and image-based velocimetry from a side perspective. Turbulence estimations were obtained for the impinging region and the roller region of the jump including Reynolds stresses, turbulent integral scales and velocity fluctuations spectra. The velocity spectra had a -5/3 slope in the inertial subrange and flattened at larger frequencies. This is thought to be linked to an energy transfer from the inertial range to the frequencies associated with bubble scales. Overall, the collected data is of particular interest for high-fidelity numerical model validation and the study represents an advancement in air-water flow research.