Assessment of dual plane PIV measurements in wall turbulence using DNS data
AuthorSaikrishnan, Neelakantan; MARUSIC, IVAN; Longmire, Ellen K.
Source TitleExperiments in Fluids
University of Melbourne Author/sMarusic, Ivan
AffiliationEngineering: Department of Mechanical and Manufacturing Engineering
Document TypeJournal (Paginated)
CitationsSaikrishnan, N., Marusic, I., & Longmire, E. K. (2006). Assessment of dual plane PIV measurements in wall turbulence using DNS data. Experiments in Fluids, 41, 265-278.
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Copyright 2006 Springer Verlag. Publisher PDF version is restricted access in accordance with the Springer Verlag policy.
Experimental dual plane particle image velocimetry (PIV) data are assessed using direct numerical simulation (DNS) data of a similar flow with the aim of studying the effect of averaging within the interrogation window. The primary reason for the use of dual plane PIV is that the entire velocity gradient tensor and hence the full vorticity vector can be obtained. One limitation of PIV is the limit on dynamic range, while DNS is typically limited by the Reynolds number of the flow. In this study, the DNS data are resolved more finely than the PIV data, and an averaging scheme is implemented on the DNS data of similar Reynolds number to compare the effects of averaging inherent to the present PIV technique. The effects of averaging on the RMS values of the velocity and vorticity are analyzed in order to estimate the percentage of turbulence intensity and enstrophy captured for a given PIV resolution in turbulent boundary layers. The focus is also to identify vortex core angle distributions, for which the two dimensional and three-dimensional swirl strengths are used. The studies are performed in the logarithmic region of a turbulent boundary layer at z+= 110 from the wall. The dual plane PIV data are measured in a zero pressure gradient flow over a flat plate at Reτ = 1,160, while the DNS data are extr acted from a channel flow at Reτ = 934. Representative plots at various wall-normal locations for the RMS values of velocity and vorticity indicate the attenuation of the variance with increasing filter size. Further, the effect of averaging on the vortex core angle statistics is negligible when compared with the raw DNS data. These results indicate that the present PIV technique is an accurate and reliable method for the purposes of statistical analysis and identification of vortex structures.
Keywordsdual plane particle image velocimetry (PIV); DNS data; Reynolds number; vortex core angle distributions
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