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Published January 1991 | public
Journal Article

Digital particle image velocimetry

Abstract

Digital particle image velocimetry (DPIV) is the digital counterpart of conventional laser speckle velocitmetry (LSV) and particle image velocimetry (PIV) techniques. In this novel, two-dimensional technique, digitally recorded video images are analyzed computationally, removing both the photographic and opto-mechanical processing steps inherent to PIV and LSV. The directional ambiguity generally associated with PIV and LSV is resolved by implementing local spatial cross-correlations between two sequential single-exposed particle images. The images are recorded at video rate (30 Hz or slower) which currently limits the application of the technique to low speed flows until digital, high resolution video systems with higher framing rates become more economically feasible. Sequential imaging makes it possible to study unsteady phenomena like the temporal evolution of a vortex ring described in this paper. The spatial velocity measurements are compared with data obtained by direct measurement of the separation of individual particle pairs. Recovered velocity data are used to compute the spatial and temporal vorticity distribution and the circulation of the vortex ring.

Additional Information

© 1991 Springer-Verlag. Received February 21, 1990. This work was sponsored by the Defense Advanced Research Project Agency-ACMP through the URI Program under contract no. DARPA/ONR N00014-86-K-0758. The authors would like to thank Mr. A. Weigand for his assistance in the vortex ring experiment.

Additional details

Created:
August 19, 2023
Modified:
March 5, 2024