Schlieren and Shadowgraph Techniques

Settles, Gary S.

doi:10.1007/978-3-642-56640-0

Cited by 1,276 publications

(415 citation statements)

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“…A 'focused' shadowgraph optical set-up, consisting of a conventional Z-type schlieren arrangement with the knife-edge removed (Settles 2006), was utilized in this study, the intent being to minimize the influence of the visualized flow features on the tracking technique to be described shortly. The focal lengths of the concave mirrors and the focusing lens were 1.5 m and 75 mm, respectively.…”

Section: Visualization Set-up and Tracking Techniquementioning

confidence: 99%

Dynamical separation of spherical bodies in supersonic flow

2012

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An experimental and computational investigation of the unsteady separation behaviour of two spheres in Mach-4 flow is carried out. The spherical bodies, initially contiguous, are released with negligible relative velocity and thereafter fly freely according to the aerodynamic forces experienced. In experiments performed in a supersonic Ludwieg tube, nylon spheres are initially suspended in the test section by weak threads which are detached by the arrival of the flow. The subsequent sphere motions and unsteady flow structures are recorded using high-speed (13 kHz) focused shadowgraphy. The qualitative separation behaviour and the final lateral velocity of the smaller sphere are found to vary strongly with both the radius ratio and the initial alignment angle of the two spheres. More disparate radii and initial configurations in which the smaller sphere centre lies downstream of the larger sphere centre each increases the tendency for the smaller sphere to be entrained within the flow region bounded by the bow shock of the larger body, rather than expelled from this region. At a critical angle for a given radius ratio (or a critical radius ratio for a given angle), transition from entrainment to expulsion occurs; at this critical value, the final lateral velocity is close to maximum due to the same 'surfing' effect noted by Laurence & Deiterding (J. Fluid Mech., vol. 676, 2011, pp. 396-431) at hypersonic Mach numbers. A visualization-based tracking algorithm is used to provide quantitative comparisons between the experiments and high-resolution inviscid numerical simulations, with generally favourable agreement.

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Section: Visualization Set-up and Tracking Techniquementioning

confidence: 99%

Dynamical separation of spherical bodies in supersonic flow

2012

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“…24,25 The benefit of colour Schlieren, used here, is that with the addition of colour it not only becomes easier to discern flow features but the intensity of the colour also gives an indication of the magnitude of the flow features.…”

Section: B Colour Schlierenmentioning

confidence: 99%

Investigation of the double ramp in hypersonic flow using luminescent measurement systems

Yang¹,

Zare‐Behtash²,

Erdem³

et al. 2012

Experimental Thermal and Fluid Science

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“…External flows Review. Hydrodynamic aspects of fish olfaction J. P. L. Cox 589 could be monitored by laser Doppler velocimetry (Kux et al 1977(Kux et al , 1978(Kux et al , 1988, particle image velocimetry (Gharib & Daribi 2000) or (possibly) by schlieren and shadowgraph techniques (Settles 2001) and internal flows by magnetic resonance imaging (Bock et al 2002;van der Linden et al 2004;Pohlmann et al 2007). These experiments would not be trivial, however, especially if one were keen not to cause the fish distress.…”

Section: Future Directionsmentioning

confidence: 99%

Hydrodynamic aspects of fish olfaction

Cox

2008

J. R. Soc. Interface.

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Flow into and around the olfactory chamber of a fish determines how odorant from the fish's immediate environment is transported to the sensory surface (olfactory epithelium) lining the chamber. Diffusion times in water are long, even over comparatively short distances (millimetres). Therefore, transport from the external environment to the olfactory epithelium must be controlled by processes that rely on convection (i.e. the bulk flow of fluid). These include the beating of cilia lining the olfactory chamber and the relatively inexpensive pumping action of accessory sacs. Flow through the chamber may also be induced by an external flow. Flow over the olfactory epithelium appears to be laminar. Odorant transfer to the olfactory epithelium may be facilitated in several ways: if the olfactory organs are mounted on stalks that penetrate the boundary layer; by the steep velocity gradients generated by beating cilia; by devices that deflect flow into the olfactory chamber; by parallel arrays of olfactory lamellae; by mechanical agitation of the chamber (or olfactory stalks); and by vortices. Overall, however, our knowledge of the hydrodynamics of fish olfaction is far from complete. Several areas of future research are outlined.

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Schlieren and Shadowgraph Techniques

Cited by 1,276 publications

References 0 publications

Dynamical separation of spherical bodies in supersonic flow

Dynamical separation of spherical bodies in supersonic flow

Investigation of the double ramp in hypersonic flow using luminescent measurement systems

Hydrodynamic aspects of fish olfaction

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