21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-3.1.2

DPIV ANALYSIS OF WALL TURBULENT SHEAR FLOWS

Gottero M., Onorato M.
Turin Polytechnical University, Italy

Keywords: dpiv, wall turbulent shear flows

The results of the DPIV analysis of the inner layer of a flat plate turbulent boundary layer, at Re=1010, in planes parallel to the wall, is presented. The streaky structure of the flow in the buffer layer is quantitatively examined. Two-dimensional Fourier analysis shows that in the buffer layer the most energetic spanwise mode occurs at the scale lambda+=250, in spite of the fact that a mean streak spacing of about lambda+=100 is visually observed. VISA technique is used to detect internal shear layers. The spatial relationship ,between the low speed streaks and internal shear layer motions is apparent in the DPIV data from planes parallel to the wall. An attempt at interpretation of the present results in the light of trains of quasi-longitudinal vortices populating , the buffer layer region is given.

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