Flow measurements

Jensen, K. D.

doi:10.1590/s1678-58782004000400006

Cited by 69 publications

(70 citation statements)

References 12 publications

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“…Each pair of images was analyzed using a crosscorrelation technique with an interrogation area of 32ϫ 32 pixels with 50% overlapping in both horizontal and vertical directions. The resulting vectors were validated by the correlation-peak-height, velocity-range, and moving-average validations; 18 the rejected vectors were replaced with interpolated values from the surrounding valid vectors. The PIV measurements were carried out only at Re= 0.4ϫ 10 5 .…”

Section: -3mentioning

confidence: 99%

Vortex shedding from a circular cylinder near a moving ground

2007

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The flow and force characteristics have been experimentally investigated of a circular cylinder with an aspect ratio of 8.33, with and without end-plates, placed near and parallel to a moving ground, on which substantially no boundary layer developed to interfere with the cylinder. Mean drag and lift measurements, surface oil flow visualization, and particle image velocimetry ͑PIV͒ measurements were carried out at two upper-subcritical Reynolds numbers of 0.4 and 1.0ϫ 10 5 ͑based on the cylinder diameter d͒ to investigate the mechanisms of the ground effect, i.e., the effect of the gap-to-diameter ratio h / d, where h is the gap between the cylinder and the ground. For the cylinder with end-plates, on which the oil flow patterns were observed to be essentially two-dimensional, the drag rapidly decreased as h / d decreased to less than 0.5 but became constant for h / d of less than 0.35, unlike that usually observed near a fixed ground. This critical drag behavior was found to be directly related to a global change in the near wake structure of the cylinder; as h / d decreased the Kármán-type vortex shedding became intermittent at h / d = 0.4, and then totally ceased and instead two nearly parallel shear layers were formed behind the cylinder at h / d = 0.3 and below. For the cylinder without end-plates, however, no such critical change in drag was observed as the Kármán-type vortices were not generated in the near wake region at all h / d investigated. Based on the experimental results obtained, further discussions are also given to the essential cause of the cessation of the Kármán vortex shedding in the ground effect.

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Section: -3mentioning

confidence: 99%

Vortex shedding from a circular cylinder near a moving ground

2007

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“…Using appropriate signal processing techniques such as spacetime diagrams and complex demodulation, it is possible to obtain spatio-temporal evolution of the flows (Bot et al, 2000). In order to obtain quantitative data on velocity fields, different velocimetry techniques have been developed such as Laser Doppler Velocimetry (LDV, Durst et al, 1976, Jensen 2004, Ultrasound Doppler Velocimetry (UDV, Takeda et al, 1994) and Particle Image Velocimetry (PIV, Jensen, 2004). Nowadays, there is a lot of literature on velocimetry techniques the development of which is beyond the scope of this chapter, some of them and their applications are described in this volume.…”

Section: Introductionmentioning

confidence: 99%

Application of the Particle Image Velocimetry to the Couette-Taylor Flow

Mutabazi¹,

Abcha

Crumeyrolle³

et al. 2012

The Particle Image Velocimetry - Characteristics, Limits and Possible Applications

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“…Particle Image Velocimetry is widely used for fluid flow study and its results are frequently used to validate simulation results [1], [9], [11], [14]. It produces instantaneous velocity vector field in 2D or 3D in case of stereographic PIV.…”

Section: B Validation Techniquementioning

confidence: 99%

“…They could be grouped as intrusive methods, which are mainly based on Constant Temperature Anemometry, for example Hot Wire Anemometry (HWA) [11], and non-intrusive ones, such as Laser Doppler Velocimetry (LDA) [12] and Particle Image Velocimetry (PIV) [13]. The PIV technique provides velocity vector fields in two-dimensional space that is used in this study.…”

Section: Introductionmentioning

confidence: 99%