Analysis of a laser Doppler anemometer

Adrian, R. J.; Goldstein, R. J.

doi:10.1088/0022-3735/4/7/006

Cited by 35 publications

(9 citation statements)

References 7 publications

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“…This has been the most important measurement technique for time-dependent measurements of the velocity in turbulent flows of water for decades. A detailed description of the fundamentals and applications of LDV can be found in Durst et al (1981) and in a more recent article by Adrian (1996).…”

Section: Laser Doppler Velocimetrymentioning

confidence: 99%

“…This interference on the detector can only occur when the wave-fronts are parallel, that is when the scattered light originates from the intersection of the scattering-and reference beams (Adrian & Goldstein, 1971). Ideally this measurement volume lies in the waist of both beams since in that case the location is well-defined and the signal-to-noise ratio is improved due to the light intensity being higher inside the smaller volume.…”

Section: Principle Of Ldvmentioning

confidence: 99%

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Experiments on free-surface turbulence

Savelsberg

Water

2009

J. Fluid Mech.

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We study the free surface of a turbulent flow, in particular the relation between the statistical properties of the wrinkled surface and those of the velocity field beneath it. Channel flow turbulence is generated using an active grid. Through a judicial choice of the stirring protocol the anisotropy of the subsurface turbulence can be controlled. The largest Taylor Reynolds number obtained is Reλ = 258. We characterize the homogeneity and isotropy of the flow and discuss Taylor's frozen turbulence hypothesis, which applies to the subsurface turbulence but not to the surface. The surface gradient field is measured using a novel laser-scanning device. Simultaneously, the velocity field in planes just below the surface is measured using particle image velocimetry (PIV). Several intuitively appealing relations between the surface gradient field and functionals of the subsurface velocity field are tested. For an irregular flow shed off a vertical cylinder, we find that surface indentations are strongly correlated with both vortical and strain events in the velocity field. For fully developed turbulence this correlation is dramatically reduced. This is because the large eddies of the subsurface turbulent flow excite random capillary–gravity waves that travel in all directions across the surface. Therefore, the turbulent surface has dynamics of its own. Nonetheless, it does inherit both the integral scale, which determines the predominant wavelength of the capillary–gravity surface waves, and the (an)isotropy from the subsurface turbulence. The kinematical aspects of the surface–turbulence connection are illustrated by a simple model in which the surface is described in terms of waves originating from Gaussian wave sources that are randomly sprinkled on the moving surface.

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Section: Laser Doppler Velocimetrymentioning

confidence: 99%

Section: Principle Of Ldvmentioning

confidence: 99%

Experiments on free-surface turbulence

Savelsberg

Water

2009

J. Fluid Mech.

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“…For example, George & Lumley (1971) have discussed the problem of transit-time broadening and, although initially overestimating its significance, have made clear its origin and paved the way for its minimization. Related information has been provided by Edwards et al (1971) and Adrian & Goldstein (1971). As indicated previously, discussions of aperture broadening and amplitude broadening in counting procedures have also been published.…”

Section: Laser Anentometry 147mentioning

confidence: 99%

“…Whitelaw include noise frequencies in its analysis. Comments on the interpretation of the Doppler spectrum can be found, for example, in Adrian & Goldstein (1971).…”

Section: Laser Anentometry 147mentioning

confidence: 99%

Laser anemometry: a report on EUROMECH 36

1972

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“…Direct fluid measurements can be taken using hot wire anemometry [1] and Laser Doppler Velocimetry (LDV) [2], which can give localized and time-resolved measurements, but all of these methods measure fluid velocity. Measuring the shear rate with these methods requires measuring a velocity component at a series of closely spaced points, from which the average slope is deduced; this requires some measurement time at each location and the region of interest must be scanned, so time-resolved measurements of shear are typically not practical with these methods.…”

Section: Introductionmentioning

confidence: 99%

Absolute measurement of laminar shear rate using photon correlation spectroscopy

Jenner

D’Urso

2015

Appl. Opt.

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Measurement of the components of the shear rate tensor S in a fluid provides insight into the properties of that fluid. We detail a refined method for performing direct and absolute measurement of the components of S in a fluid using photon correlation spectroscopy, which we show gives an absolute, accurate, noninvasive measurement of the shear rate from a single measurement at a single location. We demonstrate this method in a cone and plate rheometer, where we obtain measurements of the shear rate of water in 10 s with an absolute accuracy of 2%.

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Analysis of a laser Doppler anemometer

Cited by 35 publications

References 7 publications

Experiments on free-surface turbulence

Experiments on free-surface turbulence

Laser anemometry: a report on EUROMECH 36

Absolute measurement of laminar shear rate using photon correlation spectroscopy

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