Journal article
Near-surface turbulent dissipation at a laboratory-scale confluence: implications on gas transfer
Environmental fluid mechanics (Dordrecht, Netherlands : 2001), Vol.24(6), pp.1099-1122
12/2024
DOI: 10.1007/s10652-023-09964-8
Abstract
River confluences contribute to the outflux of saturated dissolved gases in the water resulting from high dam discharges. This process is related to gas transfer across the water-air interface, which is primarily controlled by turbulent dissipation near the water surface. However, the near-surface turbulence dissipation is rarely reported in confluence hydrodynamics studies. This study conducted experiments with different discharge ratios to investigate near-surface turbulent motions at a laboratory-scale confluence. The higher dissipation rate epsilon H/U-m(3) of near-surface turbulence was mainly located inside the interfacial shear layer between the two incoming streams (similar to 10(-4)) and the bank separation zone (10(-4)-10(-3)) where high shear was found in the mean flow. By contrast, the dissipation rates were much lower inside the incoming flows and outside the two regions of high shear (similar to 10(-5)). The magnitudes of the dissipation rate inside the shear layer were comparable in experiments where the mixing interface was in the Kelvin-Helmholtz mode or in the wake mode. The dissipation rate was found to increase away from the free surface outside the shear layer, while it was more uniformly distributed over the depth inside the layer possibly due to the presence of strongly-coherent, vertically-orientated vortices. In the far field, the mean shear within the shear layer was largely weakened. Nonetheless, the effects of flow separation persisted and laterally expanded to occupy the entire cross section. The dissipation rate epsilon H/U-m(3) of the confluent flow was more than 10(-4) even at a distance of 10 times the channel width in the post-confluence channel.
Details
- Title: Subtitle
- Near-surface turbulent dissipation at a laboratory-scale confluence: implications on gas transfer
- Creators
- Saiyu Yuan - Hohai UniversityJiawei Lin - Hohai UniversityHongwu Tang - Hohai UniversityYunqiang Zhu - Hohai UniversityQihua Ran - Hohai UniversityGeorge Constantinescu - University of IowaCarlo Gualtieri - University of Naples Federico II
- Resource Type
- Journal article
- Publication Details
- Environmental fluid mechanics (Dordrecht, Netherlands : 2001), Vol.24(6), pp.1099-1122
- Publisher
- Springer Nature
- DOI
- 10.1007/s10652-023-09964-8
- ISSN
- 1567-7419
- eISSN
- 1573-1510
- Number of pages
- 24
- Grant note
- National Natural Science Foundation of China; National Natural Science Foundation of China (NSFC) Indian Institute of Technology-Bombay
- Language
- English
- Electronic publication date
- 02/26/2024
- Date published
- 12/2024
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9984573757902771
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