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

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 imagebased 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.

Best practices for velocity estimations in highly aerated flows with dual-tip phase-detection probes

“…Largest velocities were observed for the impinging jet, followed by a shear layer and on average negative velocities in the recirculation region (figure 9a). A continuous velocity profile was attained irrespective of N p , which resembled the results presented by Zhang et al (2014) and Kramer and Valero (2019b).…”

“…The AWCC allowed the consistent characterisation of the jump's shear layer and the results were similar to observations of a jump with F r 1 = 5.43 (Zhang et al, 2014). Note that the AWCC results were further validated via image-based velocimetry from a sidewall perspective by Kramer and Valero (2019b).…”