Journal ArticleDOI
A synthetic Schlieren method for the measurement of the topography of a liquid interface
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TLDR
In this paper, an optical method for the measurement of the instantaneous topography of the interface between two transparent fluids, named free-surface synthetic Schlieren (FS-SS), is characterised.Abstract:
An optical method for the measurement of the instantaneous topography of the interface between two transparent fluids, named free-surface synthetic Schlieren (FS-SS), is characterised. This method is based on the analysis of the refracted image of a random dot pattern visualized through the interface. The apparent displacement field between the refracted image and a reference image obtained when the surface is flat is determined using a digital image correlation (DIC) algorithm. A numerical integration of this displacement field, based on a least square inversion of the gradient operator, is used for the reconstruction of the instantaneous surface height, allowing for an excellent spatial resolution with a low computational cost. The main limitation of the method, namely the ray crossing (caustics) due to strong curvature and/or large surface-pattern distance, is discussed. Validation experiments using a transparent solid model with a wavy surface or plane waves at a water–air interface are presented, and some additional time-resolved measurements of circular waves generated by a water drop impact are discussed.read more
Citations
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Journal ArticleDOI
Background-oriented schlieren (BOS) techniques
TL;DR: The main advantages of this technique, the experimental simplicity and the robustness of correlation-based digital analysis, mean that it is widely used, and variant versions are reviewed in the article.
Journal ArticleDOI
Pilot-Wave Hydrodynamics
TL;DR: In this paper, Couder et al. showed that a millimetric droplet sustained on the surface of a vibrating fluid bath may self-propel through a resonant interaction with its own wave field.
Journal ArticleDOI
Information stored in Faraday waves: the origin of a path memory
TL;DR: In this paper, the authors investigated the nature of a walker's wave field and found that it is formed by the superposition of waves emitted by the droplet collisions with the interface.
Journal ArticleDOI
Microchannel deformations due to solvent-induced PDMS swelling
TL;DR: The trajectories of droplets flowing in this microchannel are strongly affected by the deformations: drops carried by swelling oils are pushed towards the edges of the channel while those carried by non-swelling oils remain in the channel center.
Journal ArticleDOI
Decay laws, anisotropy and cyclone–anticyclone asymmetry in decaying rotating turbulence
TL;DR: In this article, the effect of background rotation on the decay of grid-generated turbulence is investigated from experiments using the large-scale ‘Coriolis’ rotating platform, where the vertical vorticity field develops a cyclone-anticyclone asymmetry, reproducing the growth law of the vertical skewness.
References
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Book
Particle Image Velocimetry: A Practical Guide
TL;DR: In this paper, the authors present a practical guide for the planning, performance and understanding of experiments employing the PIV technique, which is primarily intended for engineers, scientists and students, who already have some basic knowledge of fluid mechanics and nonintrusive optical measurement techniques.
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Performance of optical flow techniques
TL;DR: These comparisons are primarily empirical, and concentrate on the accuracy, reliability, and density of the velocity measurements; they show that performance can differ significantly among the techniques the authors implemented.
Journal ArticleDOI
Particle-Imaging Techniques for Experimental Fluid Mechanics
TL;DR: A review of these methods can be found in articles by Lauterborn & Vogel (1984), Adrian (1986a), Hesselink (1988), and Dudderar et al..
Posted Content
Digital Image Correlation: From Displacement Measurement to Identification of Elastic Properties - A Review
François Hild,Stéphane Roux +1 more
TL;DR: In this article, a general presentation of the extraction of displacement fields from the knowledge of pictures taken at different instants of an experiment is given, and different strategies can be followed to achieve a sub-pixel uncertainty.
Journal ArticleDOI
Digital Image Correlation: from Displacement Measurement to Identification of Elastic Properties – a Review
François Hild,Stéphane Roux +1 more
TL;DR: A general presentation of the extraction of displacement fields from the knowledge of pictures taken at different instants of an experiment is given, and different strategies can be followed to achieve a sub-pixel uncertainty.