Effects of Roof-Edge Roughness on Air Temperature and Pollutant Concentration in Urban Canyons
- 601 Downloads
The influence of roof-edge roughness elements on airflow, heat transfer, and street-level pollutant transport inside and above a two-dimensional urban canyon is analyzed using an urban energy balance model coupled to a large-eddy simulation model. Simulations are performed for cold (early morning) and hot (mid afternoon) periods during the hottest month of the year (August) for the climate of Abu Dhabi, United Arab Emirates. The analysis suggests that early in the morning, and when the tallest roughness elements are implemented, the temperature above the street level increases on average by 0.5 K, while the pollutant concentration decreases by 2% of the street-level concentration. For the same conditions in mid afternoon, the temperature decreases conservatively by 1 K, while the pollutant concentration increases by 7% of the street-level concentration. As a passive or active architectural solution, the roof roughness element shows promise for improving thermal comfort and air quality in the canyon for specific times, but this should be further verified experimentally. The results also warrant a closer look at the effects of mid-range roughness elements in the urban morphology on atmospheric dynamics so as to improve parametrizations in mesoscale modelling.
KeywordsEnergy balance model Large-eddy simulation Mid-range roughness element Urban canyon Urban micro-climatology
Useful discussions with Leon Glicksman and Christoph Reinhart are acknowledged. We thank Kathleen Ross for assisting Amir A. Aliabadi and Leslie K. Norford with arrangements for travelling to United Arab Emirates for a relevant workshop in Masdar Institute of Science and Technology. Assistance of Ricky Leiserson and Philip Thompson with the setting up of the simulation platform is appreciated at Massachusetts Institute of Technology (MIT). We thank Matthew Kent and Joel Best with the setting up of the simulation platform at the University of Guelph. The help of Muhammad Tauha Ali in field installations and measurements is acknowledged. We thank the reviewers of the manuscript for their careful comments. E. Scott Krayenhoff was supported by NSF Sustainability Research Network (SRN) Cooperative Agreement 1444758 and NSF SES-1520803. This work was partially funded by a Cooperative Agreement between the Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates and the Massachusetts Institute of Technology, Cambridge, MA, USA and by the National Research Foundation Singapore through the Singapore MIT Alliance for Research and Technology’s Centre for Environmental Sensing and Modelling interdisciplinary research program.
- Bredberg J (2000) On the wall boundary condition for turbulence models. Internal report 00/4, Department of Thermo and Fluid Dynamics, Chalmers University of Technology, Göteborg, Sweden, 21 ppGoogle Scholar
- Efros V (2006) Large eddy simulation of channel flow using wall functions. Thesis, Department of Thermo and Fluid Dynamics, Chalmers University of Technology, Göteborg, Sweden, 37 ppGoogle Scholar
- Greenshields CJ (2015) OpenFOAM: The Open Source CFD Toolbox, User Guide, Version 3.0.1. Tech. rep., OpenFOAM Foundation Ltd., PO Box 56676, London, W13 3DB, UK, 230 ppGoogle Scholar
- Jayatillaka CLV (1969) The influence of Prandtl number and surface roughness on the resistance of the laminar sublayer to momentum and heat transfer. Prog Heat Mass Transfer 1:193Google Scholar
- Kastner-Klein P, Berkowicz R, Britter R (2004) The influence of street architecture on flow and dispersion in street canyons. Meteorol Atmos Phys 87(1):121–131Google Scholar
- Masson V, Gomes L, Pigeon G, Liousse C, Pont V, Lagouarde JP, Voogt J, Salmond J, Oke TR, Hidalgo J, Legain D, Garrouste O, Lac C, Connan O, Briottet X, Lachérade S, Tulet P (2008) The Canopy and Aerosol Particles Interactions in TOlouse Urban Layer (CAPITOUL) experiment. Meterol Atmos Phys 102:135–157CrossRefGoogle Scholar
- Rotach MW, Vogt R, Bernhofer C, Batchvarova E, Christen A, Clappier A, Feddersen B, Gryning SE, Martucci G, Mayer H, Mitev V, Oke TR, Parlow E, Richner H, Roth M, Roulet YA, Ruffieux D, Salmond JA, Schatzmann M, Voogt JA (2005) BUBBLE-an urban boundary layer meteorology project. Theor Appl Climatol 81(3):231–261CrossRefGoogle Scholar
- Takano Y, Moonen P (2013) On the influence of roof shape on flow and dispersion in an urban street canyon. J Wind Eng Ind Aerodyn 123((Part A)):107–120Google Scholar
- White FM (2003) Fluid mechanics, 5th edn. McGraw-Hill Higher Education, New York, 866 ppGoogle Scholar