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Experimental studies of a distorted turbulent spot in a three-dimensional flow

Jahanmiri, M and Prabhu, A and Narasimha, R (1996) Experimental studies of a distorted turbulent spot in a three-dimensional flow. In: Journal of Fluid Mechanics, 329 . pp. 1-24.

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We report here on the results of a series of experiments carried out on a turbulent spot in a distorted duct to study the effects of a divergence with straight streamlines preceded by a short stretch of transverse streamline curvature, both in the absence of any pressure gradient. It is found that the distortion produces substantial asymmetry in the spot: the angles at which the spot cuts across the local streamlines are altered dramatically (in contradiction of a hypothesis commonly made in transition zone modelling), and the Tollmien-Schlichting waves that accompany the wing tips of the spot are much stronger on the outside of the bend than on the inside. However there is no strong effect on the internal structure of the spot and the eddies therein, or on such propagation characteristics as overall spread rate and the celerities of the leading and trailing edges. Both lateral streamline curvature and non-homogeneity of the laminar boundary layer into which the spot propagates are shown to be strong factors responsible for the observed asymmetry. It is concluded that these factors produce chiefly a geometric distortion of the coherent structure in the spot, but do not otherwise affect its dynamics in any significant way.

Item Type: Journal Article
Publication: Journal of Fluid Mechanics
Publisher: Cambridge university press
Additional Information: Copyright of this article belongs to Cambridge university press.
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 31 May 2011 05:30
Last Modified: 31 May 2011 05:30
URI: http://eprints.iisc.ac.in/id/eprint/37177

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