Pollutant mixing and dispersion: Turbulent Entrainment and Mixing in Turbulent Environments
Event details
| Date | 18.02.2014 |
| Hour | 16:15 › 17:15 |
| Speaker | Dr Susan Gaskin, Civil Engineering and Applied Mechanics, Mc Gill University, CA - visiting professor to CRYOS |
| Location | |
| Category | Conferences - Seminars |
Abstract:
Inland surface waters (rivers, lakes) have long been used for the disposal and transportation of waste products resulting from human activities with the ocean as the ultimate receiving body due to its assimilative capacity for large quantities of biodegradable pollutants, although conservative pollutants are also disposed of therein. The increasingly detrimental effects of these pollutants on the environment have prompted more stringent regulations. Together these motivate the study of environmental hydraulics with its concern for the disposal of and accidental spills of effluents as point releases to the atmosphere (via smoke stacks) and to surface water bodies (via outfalls), and its goal of predicting the effluent’s subsequent transport and dispersion at the local or regional scale (up to 100 km). An understanding of turbulent mixing and entrainment is crucial because the higher the initial dilution of the pollutants, the lower the impact on the environment. A remarkable property of turbulence is its capacity to mix either a vector (effluent velocity) or a scalar (pollutant) extremely rapidly and hence dilute it. Turbulent jets are effective pollutant discharge mechanisms in the near field with effluent dilution occurring due to the momentum or buoyancy driven turbulent entrainment into the turbulent jet. Effluents are released as turbulent flows into a receiving fluid (lake, river, ocean) having a range of turbulence levels. A prevailing assumption is that background turbulence will increase near field dilution due to the superposition of jet dilution and turbulent diffusion. The entrainment and mixing mechanisms of turbulent jets in quiescent ambients is reviewed. Theoretical arguments and experimental studies on the effect of turbulence in the ambient on jet dilution are shown (both a plane jet in a coflow and an axisymmetric jet in no flow). These studies contradict the prevailing assumption and indicate that near field dilution is reduced in the presence of ambient turbulence.
Short biography:
Susan Gaskin’s areas of research are in environmental hydraulics and water resources. She is an Associate Professor in the Department of Civil Engineering at McGill University, Canada, which she joined in 1997. Her interests in environmental hydraulics are in the prediction of pollutant mixing and dispersion in surface waters using experimental methods to study the turbulent mixing processes, in sediment transport and in applied hydraulics. In water resources management, her research studies both technical and management aspects of sustainable water supply management in a large project in Cameroon and on basin wide hydrologic modeling in the Basin of Mexico. She teaches courses in open channel flow, hydraulics, river engineering and water sustainability.
Inland surface waters (rivers, lakes) have long been used for the disposal and transportation of waste products resulting from human activities with the ocean as the ultimate receiving body due to its assimilative capacity for large quantities of biodegradable pollutants, although conservative pollutants are also disposed of therein. The increasingly detrimental effects of these pollutants on the environment have prompted more stringent regulations. Together these motivate the study of environmental hydraulics with its concern for the disposal of and accidental spills of effluents as point releases to the atmosphere (via smoke stacks) and to surface water bodies (via outfalls), and its goal of predicting the effluent’s subsequent transport and dispersion at the local or regional scale (up to 100 km). An understanding of turbulent mixing and entrainment is crucial because the higher the initial dilution of the pollutants, the lower the impact on the environment. A remarkable property of turbulence is its capacity to mix either a vector (effluent velocity) or a scalar (pollutant) extremely rapidly and hence dilute it. Turbulent jets are effective pollutant discharge mechanisms in the near field with effluent dilution occurring due to the momentum or buoyancy driven turbulent entrainment into the turbulent jet. Effluents are released as turbulent flows into a receiving fluid (lake, river, ocean) having a range of turbulence levels. A prevailing assumption is that background turbulence will increase near field dilution due to the superposition of jet dilution and turbulent diffusion. The entrainment and mixing mechanisms of turbulent jets in quiescent ambients is reviewed. Theoretical arguments and experimental studies on the effect of turbulence in the ambient on jet dilution are shown (both a plane jet in a coflow and an axisymmetric jet in no flow). These studies contradict the prevailing assumption and indicate that near field dilution is reduced in the presence of ambient turbulence.
Short biography:
Susan Gaskin’s areas of research are in environmental hydraulics and water resources. She is an Associate Professor in the Department of Civil Engineering at McGill University, Canada, which she joined in 1997. Her interests in environmental hydraulics are in the prediction of pollutant mixing and dispersion in surface waters using experimental methods to study the turbulent mixing processes, in sediment transport and in applied hydraulics. In water resources management, her research studies both technical and management aspects of sustainable water supply management in a large project in Cameroon and on basin wide hydrologic modeling in the Basin of Mexico. She teaches courses in open channel flow, hydraulics, river engineering and water sustainability.
Practical information
- General public
- Free
- This event is internal
Organizer
- EESS - IIE
Contact
- Prof. Michael Lehning, CRYOS