Spatial resolution of PIV for the measurement of turbulence |
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| Authors: | P Lavoie G Avallone F De Gregorio G P Romano R A Antonia |
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| Institution: | (1) Department of Aeronautics, Imperial College London, London, UK;(2) Department of Mechanics and Aeronautics, University “La Sapienza”, Rome, Italy;(3) CIRA, Italian Aerospace Center, Capua, Italy;(4) Discipline of Mechanical Engineering, University of Newcastle, Callagan, NSW, Australia |
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| Abstract: | Recent technological advancements have made the use of particle image velocimetry (PIV) more widespread for studying turbulent
flows over a wide range of scales. Although PIV does not threaten to make obsolete more mature techniques, such as hot-wire
anemometry (HWA), it is justifiably becoming an increasingly important tool for turbulence research. This paper assesses the
ability of PIV to resolve all relevant scales in a classical turbulent flow, namely grid turbulence, via a comparison with
theoretical predictions as well as HWA measurements. Particular attention is given to the statistical convergence of mean
turbulent quantities and the spatial resolution of PIV. An analytical method is developed to quantify and correct for the
effect of the finite spatial resolution of PIV measurements. While the present uncorrected PIV results largely underestimate
the mean turbulent kinetic energy and energy dissipation rate, the corrected measurements agree to a close approximation with
the HWA data. The transport equation for the second-order structure function in grid turbulence is used to establish the range
of scales affected by the limited resolution. The results show that PIV, due to the geometry of its sensing domain, must meet
slightly more stringent requirements in terms of resolution, compared with HWA, in order to provide reliable measurements
in turbulence.
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