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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Hydro-environment : A dimensional analysis of supersaturated total dissolved gas dissipation
A dimensional analysis of supersaturated total dissolved gas dissipation
Elevated levels of total dissolved gas (TDG) may occur downstream of dam discharges, leading to increased incidence of
gas bubble disease in fish. Accelerating the dissipation of supersaturated TDG in the downstream river can mitigate this
negative problem. However, developing effective mitigation techniques is hampered by limitations in present models of
TDG dissipation processes. Furthermore, data useful for modelling the dissipation of supersaturated TDG through the
free surface in natural rivers are limited. Past studies indicated that the TDG dissipation process is quantitatively different
from the reaeration process, and TDG behavior is quantitatively different from dissolved oxygen. However, a correct
parameterization of the TDG dissipation process is still missing.
The paper presents a novel dimensional analysis of the dissipation of supersaturated TDG. This approach can provide a
relationship between the TDG dissipation coefficient and some classical fluid mechanics index-numbers. This
dimensional analysis considers some key parameters for the dissipation process both water and TDG properties as well
as flow characteristics, including turbulence. These parameters are water kinematic viscosity, TDG molecular diffusivity
and vertical turbulent diffusivity, and channel width. The application of dimensional analysis pointed out that the TDG
dissipation coefficient is a function of the Schmidt number, the aspect ratio of the channel, and the shear Reynolds
number. The dimensional analysis was then verified using both field data collected in some large natural rivers and
reservoirs in Sichuan and experimental data in laboratory flume at State Key Laboratory of Hydraulics and Mountain River
Engineering of Sichuan University. The analysis revealed the key role of turbulence in controlling the TDG dissipation
while the importance of gas/water characteristics remains still unclear and needs further investigations.
File Size : 1,330,324 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Hydro-environment
Date Published : 28/08/2015
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