Integrated impacts of tree planting and street aspect ratios on CO dispersion and personal exposure in full-scale street canyons

Model tests are presented for a series of nine keels; three aspect ratios, three sweep angles; all at constant lateral area, taper ratio and thickness ratio. The series is shown to bracket current design trends. These keels are all tested on the same canoe body, over a range of heel angles, lee-ways, and speeds. The results are presented in terms of full-scale sailing performance with due allowance for a reasonable ballast ratio and resulting vertical center of gravity for each keel. Optimum sweep angles for each aspect ratio are found. A second series of three keels, geometrically similar but varying in lateral area, is provided. Predictions of windward performance demonstrate the effect of keel size. An optimum size is found for three wind strengths. The results are for one hull form only. However, a method is suggested for estimating the effect of keel size and shape for any proposed design.

Download Full-text

The influence of aspect ratios and wall heating conditions on flow and passive pollutant exposure in 2D typical street canyons

Building and Environment ◽

10.1016/j.buildenv.2019.106536 ◽

2020 ◽

Vol 168 ◽

pp. 106536 ◽

Cited By ~ 3

Author(s):

Jian Hang ◽

Xieyuan Chen ◽

Guanwen Chen ◽

Taihan Chen ◽

Yuanyuan Lin ◽

...

Keyword(s):

Street Canyons ◽

Aspect Ratios ◽

Wall Heating

Download Full-text

Large-Eddy Simulation of Reactive Pollutant Dispersion Over Street Canyons of Different Aspect Ratios

Volume 1D, Symposia: Transport Phenomena in Mixing; Turbulent Flows; Urban Fluid Mechanics; Fluid Dynamic Behavior of Complex Particles; Analysis of Elementary Processes in Dispersed Multiphase Flows; Multiphase Flow With Heat/Mass Transfer in Process Technology; Fluid Mechanics of Aircraft and Rocket Emissions and Their Environmental Impacts; High Performance CFD Computation; Performance of Multiphase Flow Systems; Wind Energy; Uncertainty Quantification in Flow Measurements and Simulations ◽

10.1115/fedsm2014-21252 ◽

2014 ◽

Cited By ~ 1

Author(s):

T. Z. Du ◽

Chun-Ho Liu ◽

Y. B. Zhao

Keyword(s):

Aspect Ratio ◽

Large Eddy Simulation ◽

Chemical Reactions ◽

Pollutant Dispersion ◽

Pollutant Removal ◽

Street Canyons ◽

Eddy Simulation ◽

Aspect Ratios ◽

Large Eddy ◽

Reactive Pollutant

In urban areas, pollutants are emitted from vehicles then disperse from the ground level to the downstream urban canopy layer (UCL) under the effect of the prevailing wind. For a hypothetical urban area in the form of idealized street canyons, the building-height-to-street-width (aspect) ratio (AR) changes the ground roughness which in turn leads to different turbulent airflow features. Turbulence is considered an important factor for the removal of reactive pollutants by means of dispersion/dilution and chemical reactions. Three values of aspect ratio, covering most flow scenarios of urban street canyons, are employed in this study. The pollutant dispersion and reaction are calculated using large-eddy simulation (LES) with chemical reactions. Turbulence timescale and reaction timescale at every single point of the UCL domain are calculated to examine the pollutant removal. The characteristic mechanism of reactive pollutant dispersion over street canyons will be reported in the conference.

Download Full-text