Record Display for the EPA National Library Catalog

RECORD NUMBER: 27 OF 93

OLS Field Name OLS Field Data
Main Title Flow and Dispersion of Pollutants within Two-Dimensional Valleys.
Author Snyder, W. H. ; Khurshudyan, L. H. ; Nekrasov, I. V. ; Lawson, R. E. ; Thompson, R. S. ;
CORP Author Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab. ;Main Geophysical Observatory, Leningrad (USSR). ;Moscow State Univ. (USSR).
Publisher c1990
Year Published 1990
Report Number EPA/600/J-90/494;
Stock Number PB91-196337
Additional Subjects Air pollution ; Dispersion ; Valleys ; Two dimensional flow ; Wind tunnel tests ; Mathematical models ; Terrain ; Diffusion ; Natural convection ; Slopes ; Eddies ; Reprints ;
Holdings
Library Call Number Additional Info Location Last
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Status
NTIS  PB91-196337 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 09/04/1991
Collation 8p
Abstract
Wind-tunnel experiments and a theoretical model concerning the flow structure and pollutant diffusion over two-dimensional valleys of varying aspect ratio are described and compared. Three model valleys were used, having small, medium, and steep slopes. Measurements of mean and turbulent velocity fields were made upstream, within, and downwind of each of these valleys. Concentration distributions were measured downwind of tracer sources placed at an array of locations within each of the valleys. The data are displayed as maps of terrain amplification factors, defined as the ratios of maximum ground-level concentrations in the presence of the valleys to the maxima observed from sources of the same height located in flat terrain. Maps are also provided showing the distance to locations of the maximum ground-level concentrations. The concentration patterns are interpreted in terms of the detailed flow structure measured in the valleys. These data were also compared with results of a mathematical model for treating flow and dispersion over two-dimensional complex terrain. The model used the wind-tunnel measurements to generate mean flow fields and eddy diffusivities, and these were applied in the numerical solution of the diffusion equation. Measured concentration fields were predicted reasonably well by the model for the valley of small slope and somewhat less well for the valley of medium slope. Because flow separation was observed within the steepest valley, the model was not applied in this case.