Shadden, S. C. and Katija, K. and Rosenfeld, M. and Marsden, J. E. and Dabiri, J. O. (2007) Transport and stirring induced by vortex formation. Journal of Fluid Mechanics, 593 . pp. 315-331. ISSN 0022-1120 http://resolver.caltech.edu/CaltechAUTHORS:SHAjfm07
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The purpose of this study is to analyse the transport and stirring of fluid that occurs owing to the formation and growth of a laminar vortex ring. Experimental data was collected upstream and downstream of the exit plane of a piston-cylinder apparatus by particle-image velocimetry. This data was used to compute Lagrangian coherent structures to demonstrate how fluid is advected during the transient process of vortex ring formation. Similar computations were performed from computational fluid dynamics (CFD) data, which showed qualitative agreement with the experimental results, although the CFD data provides better resolution in the boundary layer of the cylinder. A parametric study is performed to demonstrate how varying the piston-stroke length-to-diameter ratio affects fluid entrainment during formation. Additionally, we study how regions of fluid are stirred together during vortex formation to help establish a quantitative understanding of the role of vortical flows in mixing. We show that identification of the flow geometry during vortex formation can aid in the determination of efficient stirring. We compare this framework with a traditional stirring metric and show that the framework presented in this paper is better suited for understanding stirring/mixing in transient flow problems. A movie is available with the online version of the paper.
|Additional Information:||Copyright © Cambridge University Press 2007 Reprinted with permission. (Received 1 December 2006 and in revised form 28 August 2007). Published online 23 November 2007. The authors would like to acknowledge funding from NSF OCE-0623475 (to J.O.D.) and from NSF grant IIS-0413078 (to J.E.M.).|
|Subject Keywords:||LAGRANGIAN COHERENT STRUCTURES; RING FORMATION; APERIODIC FLOWS; POLAR VORTEX; FLUID-FLOWS; TURBULENCE; SYSTEMS; CIRCULATION; MANIFOLDS; SURFACES|
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|Deposited By:||Archive Administrator|
|Deposited On:||29 Jan 2008|
|Last Modified:||26 Dec 2012 09:49|
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