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Title: Flow and dispersion in urban areas
Author: Goulart, Elisa Valentim
ISNI:       0000 0004 2743 2700
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2012
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The threat of deliberate or accidental releases of harmful substances in urban areas makes understanding atmospheric flow and dispersion important. When the source is located within the urban canopy the highest concentrations are in the short-range, i.e. less than lkm, where the dispersion is strongly affected by the presence of buildings. Understanding the processes that govern point source dispersion in the short range is important in order to develop a dispersion model for the use of emergency responders. Some questions are addressed based on this scenario: (i) What are the main flow mechanisms in urban areas? (ii) How does a ground source disperse in the short-range? (iii) How can we model short-range dispersion for fast response applications? To answer these questions data from direct numerical simulations (DNS) over arrays of buildings are analysed. In this study two regular building arrays are used (aligned and staggered) to determine the influence of geometry on near-field dispersion. The external flow is either parallel to or oblique (45°) to the building array. Analysis of the flow field reveals a number of flow features relevant for dispersion. Firstly, when the wind is oblique to the buildings the flow divides around them, thereby causing topological splitting. Secondly, the component of the wind parallel to the streets causes channelling along the street axis. Thirdly, the flow within intersections is complex and three-dimensional, especially for oblique wind directions. Fourthly, recirculation
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available