Small scale anisotropy in axisymmetric turbulence

Douglas W. Carter, Alec J. Petersen, Filippo Coletti

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We experimentally investigate the presence of anisotropy from the inertial to the dissipative scales in homogeneous turbulence. We employ an apparatus in which two facing arrays of randomly actuated air jets generate turbulence with negligible mean flow and shear, over a volume several times larger than the energy-containing eddy size. The Reynolds number based on the Taylor microscale is varied in the range Reλ ≈ 300-500, while the axial-to-radial ratio of the root mean square velocity fluctuations ranges between 1.37 and 1.72. Two velocity components are measured by particle image velocimetry (PIV) capturing from the inertial to the Kolmogorov scales and yielding statistics up to sixth order. The scaling exponents of the velocity structure functions are found to differ not only between the longitudinal and transverse components, but also between the axial and radial directions of separation. At the dissipative scales, the moments of the velocity gradients indicate that departure from isotropy is, at the present Reynolds numbers, significant and more pronounced for stronger large-scale anisotropy. The structure-function based measures of isotropy tend towards isotropy as the separation is reduced from the inertial to the near-dissipative scales (down to about 10η, η being the Kolmogorov length) but become more anisotropic for even smaller scales which are characterized by high intermittency.

Original languageEnglish (US)
Title of host publication10th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2017
PublisherInternational Symposium on Turbulence and Shear Flow Phenomena, TSFP10
ISBN (Electronic)9780000000002
StatePublished - Jan 1 2017
Event10th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2017 - Chicago, United States
Duration: Jul 6 2017Jul 9 2017

Publication series

Name10th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2017
Volume3

Other

Other10th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2017
CountryUnited States
CityChicago
Period7/6/177/9/17

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