Zhang, X;
Simons, R;
Zheng, J;
(2020)
Experimental study of turbulent coherent structures using particle image velocimetry and hydrogen bubble visualisation techniques.
Archive of Applied Mechanics
, 91
pp. 1113-1132.
10.1007/s00419-020-01813-0.
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Abstract
The characteristics of coherent structures in turbulent boundary layers were investigated experimentally using PIV and hydrogen bubble visualisation techniques. Turbulent boundary layers were generated and tested in two flumes with different scale, for two Reynolds numbers: Re=32,000 Re=32,000 and 71,200, both over a smooth bed. Measurements from the PIV technique and hydrogen bubble visualisation lead to the same research findings, suggesting a linear relationship between the instantaneous integral spatial scale and the instantaneous spacing between turbulent streaks. This new approach to determining the streak spacing provides some guidance for experimentalists in terms of experimental methodology. Results of hydrogen bubble visualisations provide additional evidence that streamwise vortices reside near low-speed streaks. Detailed statistical analysis further demonstrates the better performance of Burr distribution for the probability density function of streak spacing. Combining the measurements of flow field in the horizontal and vertical plane, streamwise vortices are observed to be tilted ± 8∘±8∘ in the (x, z) plane and shear layers are inclined to the wall at 30∘30∘ in the (x, y) plane.
| Type: | Article |
|---|---|
| Title: | Experimental study of turbulent coherent structures using particle image velocimetry and hydrogen bubble visualisation techniques |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1007/s00419-020-01813-0 |
| Publisher version: | https://dx.doi.org/10.1007/s00419-020-01813-0 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Technology, Mechanics, Fluid dynamics, Turbulence, Bottom boundary layer, Coherent structures, Particle image velocimetry, Hydrogen bubble visualisation, NEAR-WALL REGION, DIRECT NUMERICAL-SIMULATION, LOW-SPEED STREAKS, VORTICAL STRUCTURES, VISCOUS SUBLAYER, BOUNDARY-LAYER, CHANNEL FLOW, SMOOTH, TRANSPORT |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10124431 |
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