Distortion compensation for generalized stereoscopic particle image velocimetry

Soloff, Steven M.; Adrian, Ronald J.; Liu, Zichao

doi:10.1088/0957-0233/8/12/008

Cited by 584 publications

(288 citation statements)

References 9 publications

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“…The system is based on an angular displacement of 45°of the two cameras and a 3D calibration based reconstruction method proposed by Soloff et al (1997). A special calibration grid was made to fit into the pipe and give the two cameras, which stand on either side of the light sheet, a clear view on both sides of the grid.…”

Section: Discussionmentioning

confidence: 99%

“…4 we describe the applied dewarping, reconstruction and the 3D-calibration procedure. For a more extensive description of the principles of SPIV we refer to Prasad (2000), Raffel et al (1998), Soloff et al (1997), andWillert (1997).…”

Section: Principles Of Stereoscopic-pivmentioning

confidence: 99%

“…For the combination of the two interpolated 2C-vector fields into a single 3C-vector field we make use of the 3D-calibration method proposed by Soloff et al (1997).…”

Section: Recombinationmentioning

confidence: 99%

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Measurement of laminar, transitional and turbulent pipe flow using Stereoscopic-PIV

2006

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Stereoscopic particle image velocimetry (SPIV) is applied to measure the instantaneous three component velocity field of pipe flow over the full circular cross-section of the pipe. The light sheet is oriented perpendicular to the main flow direction, and therefore the flow structures are advected through the measurement plane by the mean flow. Applying Taylor's hypothesis, the 3D flow field is reconstructed from the sequence of recorded vector fields. The large out-of-plane motion in this configuration puts a strong constraint on the recorded particle displacements, which limits the measurement accuracy. The light sheet thickness becomes an important parameter that determines the balance between the spatial resolution and signal to noise ratio. It is further demonstrated that so-called registration errors, which result from a small misalignment between the laser light sheet and the calibration target, easily become the predominant error in SPIV measurements. Measurements in laminar and turbulent pipe flow are compared to well established direct numerical simulations, and the accuracy of the instantaneous velocity vectors is found to be better than 1% of the mean axial velocity. This is sufficient to resolve the secondary flow patterns in transitional pipe flow, which are an order of magnitude smaller than the mean flow.

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Section: Discussionmentioning

confidence: 99%

Section: Principles Of Stereoscopic-pivmentioning

confidence: 99%

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Measurement of laminar, transitional and turbulent pipe flow using Stereoscopic-PIV

2006

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“…The main experimental parameters are summarized in Table I. A stereoscopic imaging mapping function 27 based on a third-order polynomial was used. An initial estimate of the mapping coefficients was obtained by means of a two-layer calibration plate (LaVision type 10) with equally spaced dots, aligned with the laser sheet within 0.5 mm precision.…”

Section: B Measurements Apparatus and Proceduresmentioning

confidence: 99%

Low-frequency behavior of the turbulent axisymmetric near-wake

et al. 2016

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The turbulent wake past an axisymmetric body is investigated with time-resolved stereoscopic particle image velocimetry (PIV) at a Reynolds number ReD = 6.7 × 104 based on the object diameter. The azimuthal organization of the near-wake is studied at different locations downstream of the trailing edge. The time-averaged velocity field features a circular shear layer bounding a region of recirculating flow. Inspection of instantaneous PIV snapshots reveals azimuthal meandering of the reverse flow region with a significant radial offset with respect to the time-averaged position. The backflow meandering appears as the major contribution to the near-wake dynamics in proximity of the base, whereas closer to the rear-stagnation point, the shear layer fluctuations become important. For x/D ≤ 0.75, the time-history and probability distributions of the backflow centroid position allow to identify this motion with an irregular precession about the model symmetry axis occurring at time scales in the order of 103 D/U∞ or higher. The first two modes obtained by snapshot proper orthogonal decomposition of the velocity fluctuations can be related to an anti-symmetric mode of azimuthal wave-number m = 1 reflecting a radial displacement of the separated flow region, while the third and fourth proper orthogonal decomposition modes are identified with a second mode pair m = 2 and are representing wake ovalization. Close to the base, a third axisymmetric mode m = 0 is identified, corresponding to a streamwise pulsation of the reverse flow region. Based on the analysis of the spatial eigen-functions and frequency spectra of the time-coefficients, it is concluded that the anti-symmetric mode m = 1 is associated with the backflow instability in the very-low frequency range StD = 10−4/10−3 close to separation, whereas more downstream it reflects the fluctuations related to the shear layer development.

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“…The correlation peaks were fitted with a three points Gaussian model. Concerning the stereoscopic reconstruction, the method first proposed by Soloff et al (1997) was used. A velocity map spanned nearly all the diffuser extension in the radial direction, whereas in the tangential one was covering an angular portion of about 14°.…”

Section: Post-processing Methods Of Piv Instantaneous Flow Fields Formentioning

confidence: 99%

Post-Processing Methods of PIV Instantaneous Flow Fields for Unsteady Flows in Turbomachines

Cavazzini¹,

Pavesi²,

Dupont³

et al. 2012

The Particle Image Velocimetry - Characteristics, Limits and Possible Applications

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The Particle Image Velocimetry is undoubtedly one of the most important technique in Fluid-dynamics since it allows to obtain a direct and instantaneous visualization of the flow field in a non-intrusive way. This innovative technique spreads in a wide number of research fields, from aerodynamics to medicine, from biology to turbulence researches, from aerodynamics to combustion processes. The book is aimed at presenting the PIV technique and its wide range of possible applications so as to provide a reference for researchers who intended to exploit this innovative technique in their research fields. Several aspects and possible problems in the analysis of large- and micro-scale turbulent phenomena, two-phase flows and polymer melts, combustion processes and turbo-machinery flow fields, internal waves and river/ocean flows were considered

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Distortion compensation for generalized stereoscopic particle image velocimetry

Cited by 584 publications

References 9 publications

Measurement of laminar, transitional and turbulent pipe flow using Stereoscopic-PIV

Measurement of laminar, transitional and turbulent pipe flow using Stereoscopic-PIV

Low-frequency behavior of the turbulent axisymmetric near-wake

Post-Processing Methods of PIV Instantaneous Flow Fields for Unsteady Flows in Turbomachines

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