Repository: Freie Universit├Ąt Berlin, Math Department

Asymptotic Vorticity Structure and Numerical Simulation of Slender Vortex Filaments

Klein, R. and Knio, O.M. (1995) Asymptotic Vorticity Structure and Numerical Simulation of Slender Vortex Filaments. Journal of Fluid Mechanics, 284 . pp. 275-321. ISSN 0022-1120

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Abstract

A new asymptotic analysis of slender vortices in three dimensions, based solely on the vorticity transport equation and the non-local vorticity-velocity relation gives new insight into the structure of slender vortex filaments. The approach is quite different from earlier analyses using matched asymptotic solutions for the velocity field and it yields additional information. This insight is used to derive three different modifications of the thin-tube version of a numerical vortex element method. Our modifications remove an O(1) error from the node velocities of the standard thin-tube model and allow us to properly account for any prescribed physical vortex core structure independent of the numerical vorticity smoothing function. We demonstrate the performance of the improved models by comparison with asymptotic solutions for slender vortex rings and for perturbed slender vortex filaments in the Klein-Majda regime, in which the filament geometry is characterized by small-amplitude-short-wavelength displacements from a straight line. These comparisons represent a stringent mutual test for both the proposed modified thin-tube schemes and for the Klein-Majda theory. Importantly, we find a convincing agreement of numerical and asymptotic predictions for values of the Klein-Majda expansion parameter E as large as 1/2. Thus, our results support their findings in earlier publications for realistic physical vortex core sizes.

Item Type:Article
Uncontrolled Keywords:Vortex flow ; Vorticity ; Non viscous fluid ; Vortices ; Equations of motion ; Asymptotic solution ; Velocity distribution ; Numerical simulation ;
Subjects:Mathematical and Computer Sciences > Mathematics > Applied Mathematics
Divisions:Department of Mathematics and Computer Science > Institute of Mathematics > Geophysical Fluid Dynamics Group
ID Code:497
Deposited By: Ulrike Eickers
Deposited On:29 Jun 2009 13:19
Last Modified:29 Jun 2009 13:19

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