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contributor authorWilson, John D.
date accessioned2017-06-09T14:09:14Z
date available2017-06-09T14:09:14Z
date copyright2004/08/01
date issued2004
identifier issn0894-8763
identifier otherams-13395.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4148840
description abstractWind statistics were measured using cup and sonic anemometers, placed upwind and downwind from a porous plastic windbreak fence (height h = 1.25 m, length Y = 114 m, resistance coefficient kr0 = 2.4, and porosity p = 0.45) standing on otherwise uniform land (short grass with roughness length z0 ? 1.9 cm). Intercomparison with collocated two-dimensional sonic anemometers suggested that, except in strongly stratified winds, cup anemometers (distance constant 1.5 m), subjected to a uniform overspeeding correction (here ?10%), provide a reasonably accurate transect of the mean wind across the disturbed flow region. The measurements, binned with respect to mean wind direction and stratification, establish that the resistance coefficient of a windbreak of this type implies the maximum (or ?potential?) mean wind reduction, a potential that is realized in neutral, perpendicular flow and for which a semiempirical formula is derived. Obliquity of the approaching wind reduces actual shelter effectiveness below the potential value, as was already known. However, a systematic influence of stratification could only be discriminated in winds that were not too far (say, within about ±30°) from perpendicular, under which conditions both stable and unstable stratification reduced shelter effectiveness. The ?quiet zone,? in which velocity standard deviations (σu, σ?) are reduced relative to the approach flow, was found to extend farther downwind for the normal velocity component (u) than for the parallel component (?).
publisherAmerican Meteorological Society
titleOblique, Stratified Winds about a Shelter Fence. Part I: Measurements
typeJournal Paper
journal volume43
journal issue8
journal titleJournal of Applied Meteorology
identifier doi10.1175/1520-0450(2004)043<1149:OSWAAS>2.0.CO;2
journal fristpage1149
journal lastpage1167
treeJournal of Applied Meteorology:;2004:;volume( 043 ):;issue: 008
contenttypeFulltext


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