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| Titel |
Schlieren visualisation and measurement of axisymmetric disturbances |
| VerfasserIn |
B. R. Sutherland, M. R. Flynn, K. Onu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 10, no. 3 ; Nr. 10, no. 3, S.303-309 |
| Datensatznummer |
250007999
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| Publikation (Nr.) |
 copernicus.org/npg-10-303-2003.pdf |
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| Zusammenfassung |
| Synthetic schlieren
is a new technique that allows one easily and inexpensively to visualise
density variations, such as those caused by internal waves propagating in
a density stratified fluid. In the special case of two-dimensional
internal waves (for example, those created by an oscillating cylinder),
synthetic schlieren allows one to measure non-intrusively the wave
amplitudes everywhere in space and time. The technique works by measuring
the apparent displacement of points in a digitised image (such as a grid
of horizontal lines), which is observed by a CCD camera through the
experimental test section. Synthetic schlieren is sufficiently sensitive
that it can measure sub-pixel-scale disturbances. In this work, we report
on the first step toward measuring fully three-dimensional disturbances.
We perform laboratory experiments in which internal waves are generated in
a uniformly salt-stratified fluid by a vertically oscillating sphere.
Theory predicts that the resulting wave-field is in the form of two cones
emanating above and below the sphere. Using inverse tomographic
techniques, we exploit the axisymmetry of the wave-field to relate the
apparent displacement of pixels in an image to the wave amplitudes. |
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