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THE INFLUENCE OF BUOYANCY ON FLOW AND POLLUTANT DISPERSION IN STREET CANYONS
Riccardo Buccolieri
; Dipartimento di Scienza dei Materiali, University of Salento, Lecce, Italy
Beatrice Pulvirenti
; Dipartimento di Ingegneria Energetica, Nucleare e del Controllo Ambientale, University of Bologna, Bologna, Italy
Silvana Di Sabatino
; Dipartimento di Scienza dei Materiali, University of Salento, Lecce, Italy
Rex Britter
; Department of Engineering, University of Cambridge, Cambridge, UK
Sažetak
In this paper, the effect of buoyancy on flow and pollutant dispersion within street canyons is studied by means of
computational fluid dynamics simulations. We consider a neutral boundary layer approaching a 3D street canyon assuming a wind
direction perpendicular to the street canyon. The Boussinesq hypothesis for incompressible fluids is chosen for modelling buoyancy.
We distinguish three cases: leeward, ground and windward wall heating. Thermal effects on both the flow and dispersion are
investigated for several Richardson numbers. The analysis focuses on the influence of street canyon geometry on flow and
temperature distribution, by considering different aspect ratios W/H canyon between 0.5 and 2, where W is the width and H the
height of the street canyon. Three-dimensional effects are observed, depending on L/H, where L is the length of the canyon. Three
dimensional effects become negligible for aspect ratio L/H larger than 20. Results obtained for the case with a large Richardson
number show that dispersion patterns in a street canyon differ substantially the isothermal case. In case with windward heating large
concentration values are found close to the windward wall. Our findings can be of interest for many urban environment applications
in which natural ventilation and thermal comfort are being of concern.
Ključne riječi
Buoyancy effects,pollutant concentration; CFD simulations; street canyon; Richardson number
Hrčak ID:
64268
URI
Datum izdavanja:
12.12.2008.
Posjeta: 1.307 *