Optical Flow Visualization

We report on the development of the optical digital interferometry (ODI) technique for measuring diffusion and Soret coefficients. The unique feature of this method is that it traces the transient path of the system in the entire two-dimensional cross section of a cell. In this way, it is applicable not only for measurements of Soret coefficients, but also for studying diffusive transport mechanism and convection. Presently, this method is not widely used and, in our view, not because of fundamental limitations but rather due to a lack of properly developed postexperimental procedures of the raw data analysis. Thus, in this paper our attention is focused on the successive analysis of different steps: the fringe analysis, the choice of reference images, the thermal design of the cell, and multiparameter fitting procedure. Using the ODI technique, we have measured the diffusion and the Soret coefficients for three binary mixtures composed of dodecane (C 12 H 26 ), isobutylbenzene, and 1,2,3,4-tetrahydronaphtalene at a mean temperature of 25 • C and 50 wt. % in each component. These measurements were compared with their benchmark values and show an agreement within less than 3%.

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“…31 For a given wavelength λ, the variation of the refractive index n(x, z) includes temperature and concentration contributions,…”

Section: B Digital Interferometrymentioning

confidence: 99%

Measurement of the Soret and diffusion coefficients for benchmark binary mixtures by means of digital interferometry

Mialdun

Shevtsova

2011

The Journal of Chemical Physics

102

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“…It is important that the oil mixture begin flowing at the desired velocity and that, after a reasonable amount of time, the surface should be relatively dry with the streaked surface pattern remaining. Refer to Merzkirch 26 for a list of candidate oils and pigments to use for various conditions. An incorrect mixture, based on the specific experimental parameters, may result in either too much pigment deposited on the surface floor, which does not result in clear streaks, or not enough pigment deposited which does not result in a streak-like pattern at all.…”

Section: Discussionmentioning

confidence: 99%

“…At the desired flow conditions, frictional forces cause the oil to move along the surface causing the pigment powder to be deposited in streaks. Critical or singularity points, locations where the shear stress is zero or two or more components of the mean velocity are zero, can be classified from the resulting skin friction line pattern as saddle points or nodal points [24][25][26] .…”

Section: Introductionmentioning

confidence: 99%

Investigating the Three-dimensional Flow Separation Induced by a Model Vocal Fold Polyp

Stewart

Erath

Plesniak

2014

JoVE

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The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. Polyps and nodules, which are geometric abnormalities that form on the medial surface of the vocal folds, can disrupt vocal fold dynamics and thus can have devastating consequences on a patient's ability to communicate. Our laboratory has reported particle image velocimetry (PIV) measurements, within an investigation of a model polyp located on the medial surface of an in vitro driven vocal fold model, which show that such a geometric abnormality considerably disrupts the glottal jet behavior. This flow field adjustment is a likely reason for the severe degradation of the vocal quality in patients with polyps. A more complete understanding of the formation and propagation of vortical structures from a geometric protuberance, such as a vocal fold polyp, and the resulting influence on the aerodynamic loadings that drive the vocal fold dynamics, is necessary for advancing the treatment of this pathological condition. The present investigation concerns the threedimensional flow separation induced by a wall-mounted prolate hemispheroid with a 2:1 aspect ratio in cross flow, i.e. a model vocal fold polyp, using an oil-film visualization technique. Unsteady, three-dimensional flow separation and its impact of the wall pressure loading are examined using skin friction line visualization and wall pressure measurements. Video LinkThe video component of this article can be found at

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“…Non-invasive methods are also commonly employed [1]. Schlieren photography and shadowgraphy are well known methods of visualising acoustic fields but lack the ability of simple pressure field quantification [2,3]. The calculation of instantaneous sound pressure using light intensity measurements has been shown to be sensitive and accurate [4].…”

Section: Introductionmentioning

confidence: 99%

A simple method for quantitative imaging of 2D acoustic fields using refracto-vibrometry

Malkin

Todd

Robert

2014

Journal of Sound and Vibration

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This paper presents a simple 2D method for rapid time resolved quantitative imaging of acoustic waves using refracto-vibrometry. We present the theoretical background, the experimental method and reconstructions of acoustic reflection and interference. We investigate the applicability of the method, in particular the effect of sound radiator geometry. Finite element and experimental reconstructions of the sound fields are analysed. The spatial limitations and accuracy of the method are presented and discussed.

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Optical Flow Visualization

Cited by 267 publications

References 191 publications

Measurement of the Soret and diffusion coefficients for benchmark binary mixtures by means of digital interferometry

Measurement of the Soret and diffusion coefficients for benchmark binary mixtures by means of digital interferometry

Investigating the Three-dimensional Flow Separation Induced by a Model Vocal Fold Polyp

A simple method for quantitative imaging of 2D acoustic fields using refracto-vibrometry

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