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Spatial and temporal variability of the concentration field from localized releases in a regular building array

Spatial and temporal variability of the concentration field from localized releases in a regular building array
Spatial and temporal variability of the concentration field from localized releases in a regular building array
Spatial and temporal fluctuations in the concentration field from an ensemble of continuous point-source releases in a regular building array are analyzed from data generated by direct numerical simulations. The release is of a passive scalar under conditions of neutral stability. Results are related to the underlying flow structure by contrasting data for an imposed wind direction of and relative to the buildings. Furthermore, the effects of distance from the source and vicinity to the plume centreline on the spatial and temporal variability are documented. The general picture that emerges is that this particular geometry splits the flow domain into segments (e.g., "streets" and "intersections") in each of which the air is, to a first approximation, well mixed. Notable exceptions to this general rule include regions close to the source, near the plume edge, and in unobstructed channels to which the flow is aligned. In the oblique ( case the strongly three-dimensional nature of the flow enhances mixing of a scalar within the canopy leading to reduced temporal and spatial concentration fluctuations within the plume core. These fluctuations are in general larger for the parallel flow ( case, especially so in the long unobstructed channels. Due to the more complex flow structure in the canyon-type streets behind buildings, fluctuations are lower than in the open channels, though still substantially larger than for oblique flow. These results are relevant to the formulation of simple models for dispersion in urban areas and to the quantification of the uncertainties in their predictions.
0006-8314
241-257
Goulart, Elisa V.
506897c3-2b95-42e1-af9e-ba09757511b6
Coceal, O.
c89d9de1-c311-4203-b6ea-b72eb48fa4f9
Branford, S.
b3cb17f7-3c04-47be-9b9e-2e9e1f102199
Thomas, T.G.
bccfa8da-6c8b-4eec-b593-00587d3ce3cc
Belcher, S.E.
c834c272-81e1-4185-b5cd-5890a9a39ea0
Goulart, Elisa V.
506897c3-2b95-42e1-af9e-ba09757511b6
Coceal, O.
c89d9de1-c311-4203-b6ea-b72eb48fa4f9
Branford, S.
b3cb17f7-3c04-47be-9b9e-2e9e1f102199
Thomas, T.G.
bccfa8da-6c8b-4eec-b593-00587d3ce3cc
Belcher, S.E.
c834c272-81e1-4185-b5cd-5890a9a39ea0

Goulart, Elisa V., Coceal, O., Branford, S., Thomas, T.G. and Belcher, S.E. (2016) Spatial and temporal variability of the concentration field from localized releases in a regular building array. Boundary-Layer Meteorology, 159 (2), 241-257. (doi:10.1007/s10546-016-0126-0).

Record type: Article

Abstract

Spatial and temporal fluctuations in the concentration field from an ensemble of continuous point-source releases in a regular building array are analyzed from data generated by direct numerical simulations. The release is of a passive scalar under conditions of neutral stability. Results are related to the underlying flow structure by contrasting data for an imposed wind direction of and relative to the buildings. Furthermore, the effects of distance from the source and vicinity to the plume centreline on the spatial and temporal variability are documented. The general picture that emerges is that this particular geometry splits the flow domain into segments (e.g., "streets" and "intersections") in each of which the air is, to a first approximation, well mixed. Notable exceptions to this general rule include regions close to the source, near the plume edge, and in unobstructed channels to which the flow is aligned. In the oblique ( case the strongly three-dimensional nature of the flow enhances mixing of a scalar within the canopy leading to reduced temporal and spatial concentration fluctuations within the plume core. These fluctuations are in general larger for the parallel flow ( case, especially so in the long unobstructed channels. Due to the more complex flow structure in the canyon-type streets behind buildings, fluctuations are lower than in the open channels, though still substantially larger than for oblique flow. These results are relevant to the formulation of simple models for dispersion in urban areas and to the quantification of the uncertainties in their predictions.

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More information

Accepted/In Press date: 4 January 2016
e-pub ahead of print date: 18 January 2016
Published date: May 2016
Organisations: Aerodynamics & Flight Mechanics Group

Identifiers

Local EPrints ID: 410450
URI: http://eprints.soton.ac.uk/id/eprint/410450
ISSN: 0006-8314
PURE UUID: 39194eb2-5dcc-4c19-83d3-e1b8d7b0b256

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Date deposited: 08 Jun 2017 16:31
Last modified: 15 Mar 2024 14:03

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Contributors

Author: Elisa V. Goulart
Author: O. Coceal
Author: S. Branford
Author: T.G. Thomas
Author: S.E. Belcher

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