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Title:Autogeneration of three-dimensional vortical structures in near wake of circular cylinder
Author(s):Mittal, Rajat; Balachandar, S.
Subject(s):Three-dimensional Vortical Structures
Near Wake
Circular Cylinder
Abstract:A direct numerical simulation has been used to study the generation and evolution of streamwise vortices in the near wake of a circular cylinder at a Reynolds number of 300. In this study, the mechanism by which streamwise vortices are generated periodically in the near wake is studied without the complicating effect of a spanwise subharmonic mode. It is observed that streamwise vortices are generated due to the stretching induced by the span wise vortices. The spanwise vortices develop significant distortions along their axis due to the action of the stream wise vortices, but large scale entrainment of vorticity from the core of the spanwise vortices into the braid region is not observed indicating that the formation of the streamwise vortices can be accomplished without such entrainment. The span wise distortion of the span wise vortices does however play a crucial role in the autogeneration process since this results in a distortion of the stretching field which in turn has a direct influence on the growth rate and location of new streamwise vortices. The evolution of the spanwise vortices is also followed closely and this provides further insight into the interaction of the various vortical structures in near wake. The current study clearly indicates that the autogeneration process involves a feedback mechanism whereby the older generation streamwise vortices play a crucial role in the generation of new streamwise vortices. Thus, this mechanism cannot be characterized within the conventional framework of core or braid instability mechanisms alone which are primarily based on the temporal evolution of the flow.
Issue Date:1995-11
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 812
Genre:Technical Report
Rights Information:Copyright 1995 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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