An improved cross correlation technique for particle image velocimetry

Abstract

The standard cross correlation technique frequently used in particle image velocimetry to extract velocity vectors necessitates the assumption that the velocity gradients inside the interrogation area are negligible. However, the procedure is generally video-based, so such an assumption may no longer be valid. This is particularly so in re-circulation zones, in which the distortion between images can be dramatic. A new iterative procedure for re-building the second image, based on velocity gradients of particles due to displacement, rotation and shear, has been proposed. This improved cross correlation algorithm has been shown to be considerably more accurate for simulated uniform, re-circulating and bi-axial shearing flows, and has been applied to the case of natural convection due to a heated horizontal cylinder.

Effect of predictor–corrector filtering on the stability and spatial resolution of iterative PIV interrogation

“…The most common choice for the displacement interpolation is bi-linear (Huang et al 1993;Jambunathan et al 1995;Scarano and Riethmuller 2000a) which is also used in the current investigation. Higher order functions have also been considered (Fincham and Delerce 2000;Lecordier and Trinité 2003), which may in principle improve the accuracy of image deformation.…”

“…The introduction of the iterative sub-pixel window shift technique (Lecordier 1997) showed that an important improvement could be obtained also in terms of measurement sub pixel precision. The iterative window deformation method (Huang et al 1993;Jambunathan et al 1995) opened the way to the development of more sophisticated algorithms able to cope with flows exhibiting a large velocity gradient minimizing correlation peak broadening. The most important improvement brought to the technique was in terms of the velocity gradient dynamic range (Fincham and Delerce 2000;Scarano and Riethmuller 2000a).…”

Influence of the Richtmyer-Meshkov instability on the kinetic energy spectrum.

“…This iteration occurred four times with a decreasing window size and increasing overlap, reaching a final size of 32x32 pixels with 50% overlap. This iterative image deformation method has been shown to improve the precision of sub-pixel displacement measurements by an order of magnitude over cross-correlation methods without image deformation [14,15].…”

‘Go with the flow ’: A review of methods and advancements in blood flow imaging

“…Particle image velocimetry (PIV) is a non-intrusive measurement technique, used to measure fullfield velocity data within a 2D plane of a particleseeded flow field [410]. The fluid velocity is inferred from the motion of tracer particles which constitute a random pattern that is 'tied' to the fluid, whose motion is visible through tracer pattern changes.…”