caa a22 4500 475777220 CHVBK 20180406123634.0 cr unu---uuuuu 170329e20000801xx s 000 0 eng 10.1023/A:1002618621171 doi (NATIONALLICENCE)springer-10.1023/A:1002618621171 A Wind-Tunnel Study of Airflow in Waving Wheat: An EOF Analysis of the Structure of the Large-Eddy Motion [Elektronische Daten] [J. Finnigan, R. Shaw] We have conducted an Empirical Orthogonal Functionanalysis (EOF) of a three dimensional, 2-pointvelocity covariance field, measured in a wind tunnel. The rate of convergence of the EOF sequence was usedas an objective test for the presence of distinctlarge turbulent structures. We found that in theroughness sublayer (2h > z > 0) the sequence convergedmuch more rapidly than in the lower surface layer(6h > z > 0), 75% of the total velocity variancebeing captured by the first three of 42 eigenmodes;h is the canopy height. The analysis was extended to three dimensions, whereover 50% of the variance and most of the spatialstructure of the covariance fields were captured by aneven smaller fraction of the total number ofeigenmodes. With some relatively weak additionalassumptions we were able to construct the velocityfield of a ‘characteristic eddy' or large coherentstructure. This consisted of a pair ofcounter-rotating streamwise vortices centred above thecanopy. The sense of rotation of the vortex pair wasopposite to that found in the wall region of boundarylayers but matched that found in plane mixing layers. A strong gust or sweep motion generated between thevortices was responsible for most of the shear stresscarried by the large eddies. The region of significanttransport of streamwise momentum by the characteristiceddy is much smaller than the region of coherence of theeddy's velocity field. Kluwer Academic Publishers, 2000 Canopy nationallicence Characteristic eddy nationallicence Empirical-orthogonal-function nationallicence Shear flow nationallicence Turbulence nationallicence Wind tunnel nationallicence Finnigan J. F.C. Pye Laboratory, CSIRO Land and Water, Canberra, Australia aut Shaw R. Davis Department of Land Air and Water Resources, University of California, Davis, U.S.A. aut Boundary-Layer Meteorology Kluwer Academic Publishers 96/1-2(2000-08-01), 211-255 0006-8314 96:1-2<211 2000 96 10546 https://doi.org/10.1023/A:1002618621171 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1002618621171 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Finnigan J. F.C. Pye Laboratory, CSIRO Land and Water, Canberra, Australia aut NATIONALLICENCE 700 1- Shaw R. Davis Department of Land Air and Water Resources, University of California, Davis, U.S.A aut NATIONALLICENCE 773 0- Boundary-Layer Meteorology Kluwer Academic Publishers 96/1-2(2000-08-01), 211-255 0006-8314 96:1-2<211 2000 96 10546 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer