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Anisotropy of the Fine Structure
Author(s) -
Kaimal J. C.,
Borkowski J.,
Panchev S.,
Gjessing D. T.,
Hasse L.
Publication year - 1969
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs004i012p01369
Subject(s) - isotropy , anisotropy , wavelength , physics , dissipation , wavenumber , turbulence , inertial frame of reference , computational physics , geometry , classical mechanics , optics , mechanics , mathematics , quantum mechanics
Kolmogorov's theory postulates that the very small scales of motion in a turbulent fluid are isotropic. At the large end of these scales (inertial subrange) the spectral energy would be expected to fall off as the − 5 3 power of wave number. Although it has been generally recognized that the − 5 3 slope in the one‐dimensional spectrum extends to wave numbers well below the limits predicted for the three‐dimensional spectrum and cannot therefore be considered a sufficient condition for isotropy, it was assumed that local isotropy could be found if the measurements went far enough into the − 5 3 region. Evidence presented at this meeting suggests that in the first few meters above the ground isotropy may never be reached even at scales small enough to be dominated by viscous dissipation. Above a height of approximately 20 meters, isotropy may be observed at wavelengths smaller than 1 10 the height above ground (i.e. a nondimensional frequency f > 10). In the free atmosphere, radio propagation experiments indicate that isotropy exists only at wavelengths of the order of 10 meters or less.