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A PIV Methodology for High-Resolution Measurement of Flow Statistics


 Particle-image velocimetry (PIV) is a flow-diagnostic technique that provides velocity fields from a comparison of images of particulate-laden flow. We have developed a PIV processing methodology that extracts measurements of the particle-displacement probability density function (PDF) from a flow video or ensemble of flow-image pairs. Single-pixel measurement of mean velocity can be obtained from an ensemble of O(103) images. Measurements of higher-order moments of the velocity PDF require spatial averaging (i.e., lower spatial resolution), larger ensembles of images, or a combination of the two. We present single-pixel-resolution PIV measurements of a steady microflow and high-resolution measurements of the velocity PDF of a stationary turbulent flow. This methodology has applications in quantifying velocity statistics in other stochastic flows, e.g., bulk and near-wall boiling.