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Numerical processing of flow-visualization pictures – measurement of two-dimensional vortex flow

Published online by Cambridge University Press:  20 April 2006

Kensaku Imaichi  and
Kazuo Ohmi
Kensaku Imaichi
Affiliation:
Faculty of Engineering Science, Osaka University, Toyonaka. Japan
Kazuo Ohmi
Affiliation:
Faculty of Engineering Science, Osaka University, Toyonaka. Japan
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Abstract

A new system has been developed for estimating experimentally some of the principal physical variables of fluid flows, through flow-visualization and image-processing techniques. Distributions of stream function, vorticity and pressure are calculated by this system with reasonable accuracy for two examples of two-dimensional flow: namely unsteady twin-vortex flow behind a circular cylinder accelerated impulsively to constant speed, and Kármán vortices behind a circular cylinder moving at constant speed. A detailed explanation of the image-processing technique and the numerical calculation process is given first, and then some consideration is given to calculated results in these two types of flow. Comparison shows that some results of the unsteady twin-vortex experiment coincide well with those of previously published experimental investigations and theoretical calculations. Errors introduced at each stage of this system are estimated in some detail.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 129 , April 1983 , pp. 283 - 311
Copyright
© 1983 Cambridge University Press

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