Experimental assessment of characteristic turbulent scales in two-phase flow of hydraulic jump: from bottom to free surface

Wang, Hang and Murzyn, Frederic (2016) Experimental assessment of characteristic turbulent scales in two-phase flow of hydraulic jump: from bottom to free surface. Environmental Fluid Mechanics, . doi:10.1007/s10652-016-9451-6


Author Wang, Hang
Murzyn, Frederic
Title Experimental assessment of characteristic turbulent scales in two-phase flow of hydraulic jump: from bottom to free surface
Journal name Environmental Fluid Mechanics   Check publisher's open access policy
ISSN 1573-1510
1567-7419
Publication date 2016-04-08
Year available 2016
Sub-type Article (original research)
DOI 10.1007/s10652-016-9451-6
Open Access Status Not Open Access
Total pages 19
Place of publication Dordrecht, Netherlands
Publisher Springer Netherlands
Collection year 2017
Language eng
Formatted abstract
A hydraulic jump is a turbulent shear flow with a free-surface roller. The turbulent flow pattern is characterised by the development of instantaneous three-dimensional turbulent structures throughout the air–water column up to the free surface. The length and time scales of the turbulent structures are key information to describe the turbulent processes, which is of significant importance for the improvement of numerical models and physical measurement techniques. However, few physical data are available so far due to the complexity of the measurement. This paper presents an investigation of a series of characteristic turbulent scales for hydraulic jumps, covering the length and time scales of turbulent flow structures in bubbly flow, on free surface and at the impingement point. The bubbly-flow turbulent scales are obtained for Fr = 7.5 with 3.4 × 104 < Re < 1.4 × 105 in both longitudinal and transverse directions, and are compared with the free-surface scales. The results highlight three-dimensional flow patterns with anisotropic turbulence field. The turbulent structures are observed with different length and time scales respectively in the shear flow region and free-surface recirculation region. The bubbly structures next to the roller surface and the free-surface fluctuation structures show comparable length and time scales, both larger than the scales of vortical structures in the shear flow and smaller than the scales of impingement perimeter at the jump toe. A decomposition of physical signals indicates that the large turbulent scales are related to the unsteady motion of the flow in the upper part of the roller, while the high-frequency velocity turbulence dominates in the lower part of the roller. Scale effects cannot be ignored for Reynolds number smaller than 4 × 104, mainly linked to the formation of large eddies in the shear layer. The present study provides a comprehensive assessment of turbulent scales in hydraulic jump, including the analyses of first data set of longitudinal bubbly-flow integral scales and transverse jump toe perimeter integral scales.
Keyword Bubbly-flow turbulent scale
Flow instability
Free-surface turbulent scale
Integral length scale
Integral time scale
Turbulent shear layer
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Civil Engineering Publications
HERDC Pre-Audit
 
Versions
Version Filter Type
Citation counts: Scopus Citation Count Cited 0 times in Scopus Article
Google Scholar Search Google Scholar
Created: Tue, 10 May 2016, 00:46:49 EST by System User on behalf of Learning and Research Services (UQ Library)