On velocity gradients in PIV interrogation

By Jerry Westerweel. 2008

201 citations recorded by the source corpus.

This paper presents a generalization of the description of the displacement-correlation peak in particle image velocimetry (PIV) to include the effects due to local velocity gradients at the scale of the interrogation domain. A general expression is derived that describes the amplitude, location and width of the displacement-correlation peak in the presence of local velocity gradients. Simplified expressions are obtained for the peak centroid and peak width for simple non-uniform motions. The results confirm that local gradients can be ignored provided that the variation of the displacement within the interrogation domain does not exceed the (mean) particle-image diameter. An additional bias occurs for a spatially accelerating or decelerating fluid, which implies an artificial "particle inertia" even when the particles can be considered as ideal tracers.

Subfields: Computational Mechanics, Global and Planetary Change, Ocean Engineering

View Paper: https://www.semanticscholar.org/paper/b9ded917d0a2a3820ad2c6c0c44b6e32336268c5

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In Computational Mechanics

In Global and Planetary Change

In Ocean Engineering

Citations in the corpus

PIV uncertainty quantification by image matching (2013, background): “This variation is ascribed to the correlation peak broadening that increases with the displacement gradient (Westerweel 2008).”
Estimation of uncertainty bounds for individual particle image velocimetry measurements from cross-correlation peak ratio (2013, methodology): “The correlation of the fluctuating signals (RD) can further be divided into an ensemble average component, 〈RD| V 〉, which carries the information about the displacement field, V , within a pair of interrogation windows, and a fluctuating component, RD, corresponding to image noise and the correlati”
Higher order multi-frame particle tracking velocimetry (2013, background): “However, when flows with strong gradients are investigated, the measurements are biased (Kähler et al. 2012a; Westerweel 2008; Keane and Adrian 1992).”
On the resolution limit of digital particle image velocimetry (2012, unknown): “3 (Keane and Adrian 1990; Westerweel 2008).”
Uncertainty on PIV mean and fluctuating velocity due to bias and random errors (2013, background): “Prasad [33], Westerweel [34], and Adrian and Westerweel [3] demonstrate optimal particle image diameters at 2.0 dτ 2.5 pixels.”