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Proceedings Paper

Unsteady flow structure in the wake of the sphere
Author(s): A. Leder; D. Geropp
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Paper Abstract

Detailed velocity data of the unsteady flow downstream of a sphere model were analyzed using a combination of a two channel Laser Doppler system and a hot wire anemometer. This set-up yields mean values at constant phase of the quasiperiodic vortex shedding process and thus delivers new insights into the instability mechanisms of a free shear layer and the forming of large scale vortices. The results show that the shearlayer instability shortly after flow separation induces an amplification of the longitudinal Reynolds normal stress component while the extremum in the transverse Reynolds normal stress is initiated by a rotating helical vortex structure which emanates from the rear end of the separation zone. The coherence length of the vortex structure is five sphere diameters D.

Paper Details

Date Published: 6 August 1993
PDF: 8 pages
Proc. SPIE 2052, Fifth International Conference on Laser Anemometry: Advances and Applications, (6 August 1993); doi: 10.1117/12.150495
Show Author Affiliations
A. Leder, Univ. Siegen (Germany)
D. Geropp, Univ. Siegen (Germany)

Published in SPIE Proceedings Vol. 2052:
Fifth International Conference on Laser Anemometry: Advances and Applications
J. M. Bessem; R. Booij; H. W. H. E. Godefroy; P. J. de Groot; K. Krishna Prasad; F. F. M. de Mul; E. J. Nijhof, Editor(s)

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