3-dimensional particle image velocimetry based evaluation of turbulent skin-friction reduction by spanwise wall oscillation

Kushal U. Kempaiah*, Fulvio Scarano, Gerrit E. Elsinga, Bas W. Van Oudheusden, Leon Bermel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
25 Downloads (Pure)


The reduction of turbulent skin-friction drag and the response of vortical structures in a zero-pressure gradient, turbulent boundary layer subjected to spanwise wall oscillation is investigated using planar and tomographic particle image velocimetry (PIV). The experiments are conducted at a momentum based Reynolds number of 1000, while the range of spanwise oscillation amplitude and frequency is chosen around the optimum reported in previous studies. A high-resolution planar PIV measurement is employed to determine the drag reduction directly from wall shear measurements and to analyze the accompanying modifications in the turbulent vortical structures. Drag reduction of up to 15% is quantified, with variations following the trends reported in the literature. The analysis of the turbulence structure of the flow is made in terms of Reynolds shear stresses, turbulence production, and vortex visualization. A pronounced drop of turbulence production is observed up to a height of 100 wall units from the wall. The vorticity analysis, both in the streamwise wall-normal plane and in the volumetric results, indicates a reduction of vorticity fluctuations in the near-wall domain. A distortion of the hairpin-packet arrangement is hypothesized, suggesting that the drag-reduction mechanism lies in the inhibition of the hairpin auto-generation by the spanwise wall oscillations.

Original languageEnglish
Article number085111
JournalPhysics of Fluids
Issue number8
Publication statusPublished - 2020

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care
Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


Dive into the research topics of '3-dimensional particle image velocimetry based evaluation of turbulent skin-friction reduction by spanwise wall oscillation'. Together they form a unique fingerprint.

Cite this