Abstract
The dispersion of material released from a point source immediately upwind of an obstacle array has been examined in a hydraulic flume with a low level of background turbulence. The main purpose of the experiments was to examine the interaction of the plume and the internal boundary layer (IBL) created over the obstacle array. The obstacle array consisted of 11 rows of cubes at 16% packing density in a staggered arrangement. Plume dispersion was measured using flow visualization with Rhodamine dye and also with a thermal tracer technique. During the experiments the source release height was varied between z = 0 and z = 4H, where H is the obstacle height. For the low-level releases, the upper boundary of the plume followed the growth of the IBL over the array. For higher level releases (z/H ≥ 2) the rate of plume growth was much reduced until the point downstream where it descended into the IBL, after which it experienced the intense turbulent mixing within the array. This suggests that the urban lateral spread parameter σy should be a strong function of height in situations where the turbulence level in the ambient approach flow is low. These results highlight the importance of the ambient turbulence even in strongly obstacle-affected dispersion.
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References
Coulson, B.J.: 1998, An experimental study of dispersion in an array of model cubes. MASc thesis, Department of Mechanical Engineering, University of Waterloo, Canada.
Davidson, M.J., Snyder, W.H., Lawson, W.E. and Hunt, J.C.R.: 1996, Wind tunnel simulations of plume dispersion through large groups of obstacles, Atmospheric Environment 30, 3715–3731.
Hall, D.J., Macdonald R., Walker, S. and Spanton, A.M.: 1998, Measurements of dispersion within simulated urban arrays — a small scale wind tunnel study. BRE Client Report CR244/98, Building Research Establishment, Garston, U.K.
Macdonald, R.W., Griffiths R.F. and Hall, D.J.: 1998, A comparison of results from scaled field and wind tunnel modelling of dispersion in arrays of obstacles, Atmospheric Environment 32, 3845–3862.
Robins, A.G.: 1999, Recent developments with the ADMS building effects module. Presented at the 2nd International Conference on Urban Air Quality, Computer Science School of the Technical University of Madrid, 3–5 March.
Robins, A. G., Hayden, P. and Teasdale, I: 1998, Dispersion from elevated sources above obstacle arrays — modelling requirements, Int. J. Env. Poll., in press
SATURN: 1999, Executive Summary, http://aix.meng.auth.gr/lhtee/saturn/lhtee/saturn.
Schatzmann, M., Leitl, B. and Liedtke, J.: 1999, Dispersion in urban environments — Comparison of field measurements with wind tunnel results. Presented at the 2nd International Conference on Urban Air Quality, Computer Science School of the Technical University of Madrid, 3–5 March.
Theurer, W., Plate, E.J. and Hoeschele, K.: 1996, Semi-empirical models as a combination of wind tunnel and numerical dispersion modelling, Atmospheric Environment 30, 3583–3597.
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© 2000 Springer Science+Business Media Dordrecht
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Macdonald, R.W., Coulson, B.J., Slawson, P.R. (2000). Near Field Dispersion in the Urban Environment — A Hydraulic Flume Study. In: Sokhi, R.S., San José, R., Moussiopoulos, N., Berkowicz, R. (eds) Urban Air Quality: Measurement, Modelling and Management. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-0932-4_25
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DOI: https://doi.org/10.1007/978-94-010-0932-4_25
Publisher Name: Springer, Dordrecht
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