Capability of air exchange rate to predict ventilation of three-dimensional street canyons

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388998%3A_____%2F19%3A00509725" target="_blank" >RIV/61388998:_____/19:00509725 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.epj-conferences.org/articles/epjconf/pdf/2019/18/epjconf_efm18_02042.pdf" target="_blank" >https://www.epj-conferences.org/articles/epjconf/pdf/2019/18/epjconf_efm18_02042.pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/epjconf/201921302042" target="_blank" >10.1051/epjconf/201921302042</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Capability of air exchange rate to predict ventilation of three-dimensional street canyons

Popis výsledku v původním jazyce

As most of the world’s population lives in cities, it is critical to understand dispersion processes of pollutants in urban areas. This study focuses on so called air exchange rate (ACH) index, which is frequently used by numerical studies to determine ventilation of street canyons without a simulation of a pollution source. These studies applied the ACH on idealised 2D street canyons, where the ventilation acts only through the one opening roof top. There are two pertinent questions: i) is the ACH really capable to predict the ventilation of a street canyon without knowing of a pollutant source, and ii) how much the ACH differs between 2D and 3D street canyons? To answer these questions, we performed large-eddy simulations of pollution of complex 3D street canyons from ground-level line sources. We computed ACHs and spatially-average concentrations for three different street canyons and compared these quantities with those from previous studies. Results clearly demonstrate that these quantities strongly depend not only on street-canyon geometry but also on geometry of surrounding buildings. It is also shown that 2D canyon gives unrealistic result for retention of pollutant within an urban street canyon. The ACH might lead to significant underestimation of the street-canyon ventilation if a source would be outside the canyon.

Název v anglickém jazyce

Capability of air exchange rate to predict ventilation of three-dimensional street canyons

Popis výsledku anglicky

As most of the world’s population lives in cities, it is critical to understand dispersion processes of pollutants in urban areas. This study focuses on so called air exchange rate (ACH) index, which is frequently used by numerical studies to determine ventilation of street canyons without a simulation of a pollution source. These studies applied the ACH on idealised 2D street canyons, where the ventilation acts only through the one opening roof top. There are two pertinent questions: i) is the ACH really capable to predict the ventilation of a street canyon without knowing of a pollutant source, and ii) how much the ACH differs between 2D and 3D street canyons? To answer these questions, we performed large-eddy simulations of pollution of complex 3D street canyons from ground-level line sources. We computed ACHs and spatially-average concentrations for three different street canyons and compared these quantities with those from previous studies. Results clearly demonstrate that these quantities strongly depend not only on street-canyon geometry but also on geometry of surrounding buildings. It is also shown that 2D canyon gives unrealistic result for retention of pollutant within an urban street canyon. The ACH might lead to significant underestimation of the street-canyon ventilation if a source would be outside the canyon.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

10509 - Meteorology and atmospheric sciences

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

EPJ Web of Conferences

ISBN

—

ISSN

2100-014X

e-ISSN

—

Počet stran výsledku

6

Strana od-do

02042

Název nakladatele

EDP Sciences

Místo vydání

Paris

Místo konání akce

Prague

Datum konání akce

13. 11. 2018

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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