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Flow structure in a model of aircraft trailing vortices

Faddy, J. M. and Pullin, D. I. (2005) Flow structure in a model of aircraft trailing vortices. Physics of Fluids, 17 (8). Art. No. 085106. ISSN 1070-6631. http://resolver.caltech.edu/CaltechAUTHORS:FADpof05

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Abstract

We consider a model of incompressible trailing vortices consisting of an array of counter-rotating structures in a doubly periodic domain, infinite in the vertical direction. The two-dimensional vortex array of Mallier and Maslowe is combined with an axial velocity profile chosen proportional to the initial axial vorticity to provide an initial condition for the vortex wake. This base flow is a weak solution of the steady Euler equations with three velocity components that are functions of two spatial coordinates, thus allowing its linear stability properties to be investigated. These are used to interpret several stages in the development of vortex structure observed in fully three-dimensional direct numerical simulation (DNS) at Reynolds numbers Gamma/(2pinu)=[script O](1000). For sufficiently high axial velocity, its effect can be seen, in that each vortex in the linear array first develops helical structures before undergoing a period of relaminarization. At later times the more slowly growing cooperative elliptical instabilities become apparent, but the helical structure persists and the observed vortical structures remain coherent for longer periods than in the absence of axial velocity. Using the stretched-vortex subgrid model, large-eddy simulation runs are performed at large Reynolds numbers and a mixing transition identified at about Re=1–2×10^4. Similar phenomena are observed in these simulations as are seen in the DNS.


Item Type:Article
Additional Information:©2005 American Institute of Physics (Received 8 December 2004; accepted 27 May 2005; published online 23 August 2005) The authors (J.M.F. and D.I.P.) were supported in part by the National Science Foundation under Grant No. CTS-0227881. Access to the Hewlett-Packard V2500 computer, located at the California Institute of Technology, was provided by the Center for Advanced Computing Research.
Subject Keywords:aerodynamics; vortices; wakes; flow simulation; flow instability; turbulence
Record Number:CaltechAUTHORS:FADpof05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:FADpof05
Alternative URL:http://dx.doi.org/10.1063/1.1955536
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2500
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:06 Apr 2006
Last Modified:26 Dec 2012 08:49

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