Emissions in street canyons 2

Experiments by

S.Rafailidis and M.Schatzmann

Summary

The objective of this experiment is to provide a simulation of toxic emissions from vehicle exhausts in a street canyon within an urban environment. In particular, an investigation is made into the effect on measured concentrations of different street widths and different shapes of the roofs of nearby buildings.

The experiments are two-dimensional - being conducted with buildings lying completely across the wind tunnel. Between two of the buildings, there is a steady line source (also lying completely across the wind tunnel) in a street canyon. The wind is orthogonal to the direction of the street, and there are buildings at regular intervals both upstream and downstream of the street containing the source, simulating a built-up urban environment.

Concentrations are measured on various building faces and presented in dimensionless form. The results indicate that pollutant concentration from street level emissions in an urban environment may depend significantly on the shapes of the building roofs, as well as on the street width to building height ratio.

The experiments are described in more detail in the following chapters:

1. Summary of Experimental Set-up
2. Summary of Results
3. Discussion and Conclusions

Editor's note: In preparing this summary for the World Wide Web it has been my objective to make available a short summary of these experiments in the form: what was done? what were the results? and what might they mean? The results of the experiments will be of interest to those making mathematical models of dispersion in obstructed flows, and I have aimed to present enough information for model validation purposes here. However this treatment does not, and can not, do justice to the immense amount of care taken by the experimenters to ensure that the results are meaningful and significant. For example, I have not mentioned that measurements were made at different points across the tunnel to ensure that a two-dimensional flow was indeed being observed. (They were and it was.) And this is no place to go into the subtleties of experimental technique and the problems overcome. For that, and for any other details I may have missed out advertantly or otherwise, the reader is referred to the original work cited below. - DMW, October 1996

This summary is based on "Concentration Measurements with Different Roof Patterns in Street Canyons with Aspect Ratios B/H=1/2 and B/H=1", S Rafailidis and M Schatzmann, Universität Hamburg, Meteorologisches Institut, (1995).

If you really need a copy of this report with all the experimental details, then please e-mail one of the authors: M Schatzmann or S Rafailidis. (If you need to do this, it would be helpful if you could indicate what particular information you feel is lacking from these pages.)

Experiments by S Rafailidis and M Schatzmann
Summary for the World Wide Web by D M Webber
These pages Copyright © 1996 Universität Hamburg, Meteorologisches Institut
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