Taylor and Lagrange correlations in a turbulent free shear layer |
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Authors: | E Loth J Stedl |
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Institution: | (1) University of Illinois at Urbana-Champaign 306 Talbot Lab., MC-236 104 S. Wright St. Urbana, IL 61801, USA, US |
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Abstract: | The objective of this research was to study the effect of various Lagrange-tracking correlation methods in estimating the
eddy lifetime for a two-stream, turbulent, planar free shear layer. Zeroth-, first- and second-order Lagrange correlation
methods were applied to the time-evolving velocity field data collected from a cinematic particle image velocimetry technique.
A time scale associated with the eddy lifetime was obtained based on a 2/e correlation of either vorticity or streamwise velocity fluctuations. When based on vorticity, this time scale significantly
increased as expected when the tracking was computed with a second-order Lagrangian tracking technique as compared to a (zeroth-order)
Taylor hypothesis approach. However when based on streamwise velocity fluctuations, this time scale did not increase significantly
for the higher order projection methods. The latter result is attributed to occurrences of “reverse correlation” of the instantaneous
streamwise velocity fluctuations caused by eddy rotation.
Received: 2 April 1997/Accepted: 3 September 1997 |
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Keywords: | |
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