Record Display for the EPA National Library Catalog


Main Title Experiments on Stably and Neutrally Stratified Flow Over a Model Three-Dimensional Hill.
Author Hunt, J. C. R. ; Snyder, William H. ;
CORP Author Environmental Sciences Research Lab., Research Triangle Park, NC. Meteorology and Assessment Div.
Year Published 1980
Report Number EPA-600/J-80-025;
Stock Number PB80-196942
Additional Subjects Wind(Meteorology) ; Hills ; Stratification ; Froude number ; Flow separation ; Flow visualization ; Unsteady flow ; Air pollution ; Reprints ; Atmospheric boundary layer ; Atmospheric dispersion
Library Call Number Additional Info Location Last
NTIS  PB80-196942 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 38p
The flow structure over a bell shaped hill (reciprocal of a fourth order polynomial in cross section and height h) was studied in large and small stably stratified towing tanks (with uniform density gradients) and in an unstratified wind tunnel. Observations were made at Froude numbers F=U/(Nh) over the range 0.1 to 1.7 and at F=infinity (U is the towing speed and N is the Brunt-Vaisala frequency). For F greater than or equal to 0.4, the observations verify Drazins' (1961) theory for low Froude number flow over 3-dimensional obstacles and establish limits of applicability. For Froude numbers of order 1, the study shows that a classification of the lee wave patterns and separated flow regions observed in 2-dimensional flows also appears to apply to 3-dimensional hills. Flow visualization techniques were used extensively to produce both qualitative and quantitative information on the flow structure around the hill. Representative photographs of dye tracers, potassium permanganate dye streaks, shadowgraphs, surface dye smears, and hydrogen bubble patterns are included. While emphasis is centered on obtaining a basic understanding of flow around 3-dimensional hills, the results are applicable to estimating air pollutant dispersion around hills.