EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Thoroddsen & Van Atta 1992
Thoroddsen, S.T. and Van Atta, C.W. (1992). The influence of stable stratification on small-scale anisotropy and dissipation in turbulence. Journal of Geophysical Research 97: doi: 10.1029/91JC02727. issn: 0148-0227.

Small-scale turbulence measurements in stably stratified grid-generated turbulence show that strong stable stratification induces large anisotropies in the mean-square strain rates ∂v/∂x and ∂w/∂x, relative to ∂u/∂x. This effect is magnified with increased strength of stratification. Froude number scaling is partially successful in collapsing the data. Anisotropies of the strain rates associated with the small scales are found to develop relatively faster than the anisotropy of the large-scale energy containing eddies. The mean-square magnitude of the ∂w/∂x strain rate is up to 4 times lower than the level predicted from ∂u/∂x based on isotropy. These results cast doubt on the accurcy of employing conventional dissipation estimates based on the assumption of local isotropy in stratified turbulence, at least for the low Reynolds numbers characterizing these experiments. These results are especially relevant to ocean microscale measurements, as buoyancy affected turbulence with similar dynamical character, i.e., &egr;/&ngr;N2 of similar magnitudes, has been observed in the thermocline (see Gregg and Sanford, 1988; Yamazaki, 1990). Estimates of dissipation rates based on the formulations of Stillinger et al. (1983) and Yamazaki and Osborn (1990) are shown to disagree by as large as a factor of 2. The measurements also show that stable stratification induces anisotropy in the lateral horizontal rms velocity component in addition to the well-known vertical anisotropy. The lateral anisotropy is about half of the vertical anisotropy. Measured spectral relations between the streamwise and lateral velocity components in the horizontal plane were compared with relations predicted by the two- and three-dimensional (2-D and 3-D) isotropic theories. Comparison of measured and calculated lateral spectra indicate no tendency toward the development of 2-D turbulence in the range of Froude numbers studied. ¿ American Geophysical Union 1992

BACKGROUND DATA FILES

Abstract

Keywords
Oceanography, Physical, Fine structure and microstructure, Oceanography, Physical, Turbulence, diffusion, and mixing processes, Oceanography, Physical, Instruments and techniques
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit