Directional ambiguity resolution in particle image velocimetry by pulse tagging

Grant, Ian; Liu, A.

doi:10.1007/bf00215013

Cited by 28 publications

(7 citation statements)

References 10 publications

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“…Details of the method are presented elsewhere (Grant and Liu 1989). Where directional ambiguity occurred in the images this could be resolved either by images shifting at the experimental stage (Grant et al 1988) or by pulse tagging (Grant and Liu 1990). Regions of isovelocity flow were rapidly identified using convolution filtering techniques where appropriate (Grant and Qiu 1990) as a precursor to particle-by-particle analysis.…”

Section: The Image Processormentioning

confidence: 99%

Particle image velocimetry measurements of the separated flow behind a rearward facing step

Grant

Owens

Yan

et al. 1992

Experiments in Fluids

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Section: The Image Processormentioning

confidence: 99%

Particle image velocimetry measurements of the separated flow behind a rearward facing step

Grant

Owens

Yan

et al. 1992

Experiments in Fluids

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“…Early works dealt with planar illumination, mostly, and the problem of truncated traces by out-of-plane motion was approached by using a dot-streak-dot encoding of the particle image (Agüí and Jimenez, 1990). A solution to the problem of directional ambiguity was proposed by Grant and Liu (1990), with the pulse tagging technique, whereby the preceding and following pulses were differing in their intensity. Even though the research shifted its focus towards algorithms for the analysis of single-frame single exposure recordings, ME or streaks analysis maintain its research scope (Qureshi and Tien, 2022, among others).…”

Section: Introductionmentioning

confidence: 99%

“…from Utami and Ueno, 1980); pulse-streak-pulse (repr. from Agui and Jimenez, 1990); Pulse-tagging (repr.fromGrant and Liu, 1990); Streak velocimetry (repr. fromQureshi and Tien, 2022)…”

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confidence: 99%

Asymmetric time-sequence for multiple-exposure 3D PTV

Scarano,

Hysa,

Guerra

et al. 2024

Preprint

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Making use of a single-frame to record multiple exposures (ME) of the tracer particles has the potential to simplify the hardware needed for 3D PTV measurements, especially when dealing with high-speed flows. The analysis of such recordings, however, is challenged by the unknown time-tag of each particle exposure, alongside their unknown organization into physical trajectories (trajectory-tag). Using a sequence of illumination pulses with a constant time separation leads to the well-known directional ambiguity problem, whereby it is not possible to distinguish the direction of motion of the tracer particles. Instead, coding the temporal information into a specific sequence of illumination pulses with irregular time separation results in a unique sequence of positions in the image, similar to a trace. The asymmetric pattern of the trace needs to be recognized, and a kinematic similarity criterion is introduced that selects traces most similar to the time sequence. Combining the latter with a criterion that favors trace regularity (minimum velocity fluctuations). The numerical implementation of the technique is challenged by the combinatorial growth of the calculations. The algorithm is applied to a 3D experiment and results are benchmarked against the time-resolved analysis (single-frame, single-exposure) with the Shake-the-Box method. Traces with a three-pulses yield a detection rate of 85%. The latter declines with the number of pulses. Conversely, the error rate rapidly vanishes with the samples number, which confirms the reliability of trace detection criterion when more pulses are comprised in the sequence. Potential methods to accelerate the ME recordings analysis are presented. The remaining bottlenecks hampering the direct application of the technique are also introduced and shortly discussed.

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“…The detection of the sign of particle velocity vectors is a classical problem of PIV analysis [19,20]. In fact, most of the proposed solutions are only capable of evaluating the magnitude and direction line of the velocity vector, without the sign.…”

Section: Introductionmentioning

confidence: 99%