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On the possibilities to use CFD for dispersion modelling in urban surroundings
FOI. (Luval)
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2017.
National Category
Meteorology and Atmospheric Sciences
Research subject
Meteorology
Identifiers
URN: urn:nbn:se:uu:diva-320319OAI: oai:DiVA.org:uu-320319DiVA, id: diva2:1089233
Available from: 2017-04-24 Created: 2017-04-19 Last updated: 2017-04-24
List of papers
1. On possibilities to estimate concentration variations with CFD in urban environments
Open this publication in new window or tab >>On possibilities to estimate concentration variations with CFD in urban environments
(English)Article in journal (Refereed) Submitted
Place, publisher, year, edition, pages
Uppsala:
National Category
Meteorology and Atmospheric Sciences
Research subject
Meteorology
Identifiers
urn:nbn:se:uu:diva-320318 (URN)
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-04-24
2. Issues when linking computational fluid dynamics for urban modeling to toxic load models: The need for further research
Open this publication in new window or tab >>Issues when linking computational fluid dynamics for urban modeling to toxic load models: The need for further research
2015 (English)In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 104, p. 112-124Article in journal (Refereed) Published
Abstract [en]

In order to predict casualties caused by chemical hazards in densely populated areas, state-of-the-art Computational Fluid Dynamic (CFD) techniques could be utilized together with toxic load models. In the current study, simulations of consequences of hypothetical releases of toxic gas in a city center are presented and discussed. CFD models that reproduce flow statistics would be most appropriate for this purpose since it could be expected that they will more realistically represent the environment. However, since concentration-peaks in the ever-present spatiotemporal fluctuations of airborne chemicals contribute so much to the toxic load, it is shown that straight-forward direct linking of a CFD model to a toxic load model is not a suitable approach for predicting consequences of a toxic release. Furthermore, it is demonstrated that the use of different turbulence models leads to different casualty assessments. Obviously, there is an urgent need to establish widely accepted methods, ideally with known uncertainty measures. Thus, further research in this area is of great importance.

Keywords
Chemical hazard, Casualty assessments, Urban area, CFD, Toxic load
National Category
Meteorology and Atmospheric Sciences
Research subject
Meteorology
Identifiers
urn:nbn:se:uu:diva-320317 (URN)10.1016/j.atmosenv.2014.12.068 (DOI)000350189000012 ()
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-04-24Bibliographically approved
3. Estimation of Efficient Height of Buildings for Urban Dispersion Models
Open this publication in new window or tab >>Estimation of Efficient Height of Buildings for Urban Dispersion Models
2014 (English)In: Air Pollution Modeling and Its Application XXII / [ed] Douw G. SteynPeter J.H. BuiltjesRenske M.A. Timmermans, 2014, p. 653-656Conference paper, Published paper (Refereed)
Abstract [en]

The purpose of the study was to establish an efficient height for block buildings used as geo-data by simplified urban dispersion models when the buildings in the Real world could have gabled roofs or carry a lot of objects as chimneys, antennas and other things. Assuming that CFD with RANS models can mimic the Real world, comparisons are made on the flow around buildings. Efficient height is defined as the height of a flat roof building when the flow around it most resembles the flow around a building with another shape. The results indicate that the efficient height should be somewhere between just below rooftop height and rooftop height + 5 m. But most of the results indicate that the efficient height should be close to the roof top value.

Series
NATO Science for Peace and Security Series C-Environmental Security, ISSN 1871-4668
Keywords
Urban dispersion, CFD-RAMS, Building influence
National Category
Meteorology and Atmospheric Sciences
Identifiers
urn:nbn:se:uu:diva-320316 (URN)10.1007/978-94-007-5577-2_110 (DOI)000339389900109 ()9789400755772 (ISBN)9789400755765 (ISBN)
Conference
32nd NATO/SPS International Technical Meeting on Air Pollution Modeling and its Application, Utrecht, NETHERLANDS, MAY 07-11, 2012
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-04-24Bibliographically approved
4. An evaluation of topographical effects on neutral and heavy-gas dispersion with a CFD model
Open this publication in new window or tab >>An evaluation of topographical effects on neutral and heavy-gas dispersion with a CFD model
1998 (English)In: Journal of Wind Engineering and Industrial Aerodynamics, ISSN 0167-6105, E-ISSN 1872-8197, Vol. 74, no 6, p. 315-325Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

Three different scenarios are studied to estimate how different structures at the side of a road, influence concentration levels. A solid fence gives the strongest effect on concentration. It forces the mean flow to move vertically which promotes mixing in the wake behind the fence. A hedge reduces the level of turbulence and the level of concentration becomes higher due to less turbulent dispersion. A road-valley generates turbulence in an intermediate regime. It captures a part of the plume in the valley which gives high concentrations locally. Atmospheric stability increases the concentration levels at a distance from the topographical disturbance. A heavy gasplume encountering a solid fence is broadened in front of the fence depending on the height of the fence and internal stability in the plume. The relation between these parameters, wind speed and the source rate will also affect the level of concentration downwind the fence.

Keywords
topographical effects, heavy gas, dispersion, kappa-epsilon
National Category
Meteorology and Atmospheric Sciences
Research subject
Meteorology
Identifiers
urn:nbn:se:uu:diva-320315 (URN)10.1016/S0167-6105(98)00028-2 (DOI)000075383400026 ()
Conference
2nd European and African Conference on Wind Engineering, GENOA, ITALY, JUN 22-26, 1997
Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-04-24Bibliographically approved

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