Relationship investigation between the dissipation process of supersaturated total dissolved gas and wind effect

摘要

The elevated supersaturation of total dissolved gas (TDG) downstream of high-dam spills may lead to gas bubble disease or mortality in fish. Wind velocity is an important factor in accelerating the dissipation process of TDG. The accurate simulation and assessment of the dissipation process of supersaturated TDG are hampered by the scarcity of a quantitative description of the wind effect on the TDG dissipation process. The wind-driven experiments in this paper quantified the dissipation coefficients of supersaturated TDG under different wind velocities. A dimensionless ratio number, r, which represents the ratio between the dissipation coefficient with wind, K-w, and the coefficient without wind, K-0, was introduced. A formula was developed to quantify the relationship between the dimensionless ratio number r and the wind velocity. The quantitative relationship was applied in a three-dimensional simulation to investigate the transportation and dissipation process of TDG in the wind-driven flow. The eddies generated by the wind-driven flow, which greatly contributed to the dissipation of TDG, and the spatial and temporal evolution of supersaturated TDG were obtained and were in good accordance with the measured data. The investigation provides a quantitative basis for the accurate prediction of the dissipation process of supersaturated TDG at different wind velocities. (C) 2016 Elsevier B.V. All rights reserved.