Measurement of the gradient field of a turbulent free surface

Savelsberg, Ralph; Holten, Apc Ad; Water, Willem van de

doi:10.1007/s00348-006-0186-x

Cited by 23 publications

(27 citation statements)

References 18 publications

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“…The scanning technique is explained in Ref. 22. Briefly, the laser beam is swiveled by a mirror oscillating at 2 kHz, and the PSD is read out synchronously.…”

Section: -2mentioning

confidence: 99%

“…The scanning frequency restricts the highest detectable frequency of the surface waves to 1 kHz, but larger frequencies ͑and larger signal to noise ratio͒ are accessible in measurements of ٌh͑t͒ in a point. 22 …”

Section: -2mentioning

confidence: 99%

“…1; it has a smaller dynamical range while the signal to noise ratio is limited by the fast scanning in combination with the time response of the PSD. 22 This is illustrated in Fig. 3 where we compare the frequency spectrum ͑averaged over the line͒ with the frequency spectrum of a point measurement.…”

Section: Space-time Measurementsmentioning

confidence: 99%

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Turbulent parametric surface waves

2009

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We study disordered capillary waves on the surface of a vertically oscillated fluid layer and try to establish their relation with weak wave turbulence. We measure the surface gradient in space and time and argue that gradient spectra are better suited for comparison to the predictions of weak wave turbulence theory than spectra of the surface elevation. Because the gradient is a vector quantity, we must distinguish longitudinal and transverse spectra. However, they prove to be related trivially through isotropy. From the measured wavenumber-frequency spectrum it appears that the dispersion relation is only satisfied approximately. In the wavenumber direction the spectral features are strongly broadened due to spatial disorder. This disagrees with weak wave turbulence theory where exact satisfaction of the dispersion relation is pivotal. We find approximate algebraic frequency and wavenumber spectra but with exponents that are different from those predicted by weak wave turbulence theory. However, other findings, such as the broadening of harmonics proportional to their frequency and the emergence of Gaussian statistics at selected wavenumber bands, point to weak wave turbulence.

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“…The scanning technique is explained in Ref. 22. Briefly, the laser beam is swiveled by a mirror oscillating at 2 kHz, and the PSD is read out synchronously.…”

Section: -2mentioning

confidence: 99%

Section: -2mentioning

confidence: 99%

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Turbulent parametric surface waves

2009

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“…As turbulence is a statistical phenomenon, the question is how to devise statistical quantities that can capture these phenomena. For example, for vortices attached to the surface one would expect a strong correlation between the surface height and the rotation of the velocity field just beneath it, while for upwellings and downdraughts the strongest correlation would be between the surface height and the strain.We have developed a new precise and linear laser scanner to measure the surface gradient field [8]. By combining this with particle image velocimetry to measure the velocity field in a plane just beneath the surface, we will address the relation between the surface crispations and the velocity field.…”

mentioning

confidence: 99%

“…We have developed a new precise and linear laser scanner to measure the surface gradient field [8]. By combining this with particle image velocimetry to measure the velocity field in a plane just beneath the surface, we will address the relation between the surface crispations and the velocity field.…”

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confidence: 99%

Turbulence of a Free Surface

Savelsberg

Water

2008

Phys. Rev. Lett.

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We study the free surface of a turbulent channel flow, in particular, the relation between the statistical properties of the wrinkled surface and those of the velocity field beneath it. For an irregular flow shed off a vertical cylinder, surface indentations are strongly correlated with vortices in the subsurface flow. For fully developed turbulence this correlation is dramatically reduced. This is because the large eddies excite random capillary-gravity waves that travel in all directions across the surface. Both their predominant wavelength and their anisotropy are determined by the subsurface turbulence.

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Measurements of Surface Deformation in Highly-Reflecting Liquid-Metals

Gutiérrez

Padilla

Aumaître

2015

Springer Proceedings in Physics

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International audienceWe present an experimental study of surface deformation in a liquid metal. The investigation has two main parts. First we present an optical setup allowing to obtain the surface profile along a line, for a highly-reflecting liquid-metal. We track the diffusion of a laser sheet on the surface from two opposite angles, avoiding saturations due to specular reflection. In the second part, the technique is used to study some aspects of the wave-vortex interaction problem. Special attention is given to the surface deformation produced by a flow composed by moving vortices. Asymmetric height statistics are observed and discussed. Some indications of wave emission are presented. Finally, the attenuation of propagating waves by the same flow is briefly discussed

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Measurement of the gradient field of a turbulent free surface

Cited by 23 publications

References 18 publications

Turbulent parametric surface waves

Turbulent parametric surface waves

Turbulence of a Free Surface

Measurements of Surface Deformation in Highly-Reflecting Liquid-Metals

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