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The spiral wind-up and dissipation of vorticity and a passive scalar in a strained planar vortex

Citation

Bassom, AP and Gilbert, AD, The spiral wind-up and dissipation of vorticity and a passive scalar in a strained planar vortex, Journal of Fluid Mechanics, 398 pp. 245-270. ISSN 0022-1120 (1999) [Refereed Article]

Copyright Statement

Copyright 1999 Cambridge University Press

DOI: doi:10.1017/S0022112099006278

Abstract

The response of a Gaussian vortex to a weak time-dependent external strain field is studied numerically. The cases of an impulsive strain, an on–off step function, and a continuous random strain are considered. Transfers of enstrophy between mean and azimuthal components are observed, and the results are compared with an analogous passive scalar model and with Kida's elliptical vortex model.

A ‘rebound’ phenomenon is seen: after enstrophy is transferred from mean to azimuthal component by the external straining field, there is a subsequent transfer of enstrophy back from the azimuthal component to the mean. Analytical support is given for this phenomenon using Lundgren's asymptotic formulation of the spiral wind-up of vorticity. Finally the decay of the vortex under a continuous random external strain is studied numerically and compared with the passive scalar model. The vorticity distribution decays more slowly than the scalar because of the rebound phenomenon.

Item Details

Item Type:Refereed Article
Research Division:Mathematical Sciences
Research Group:Applied Mathematics
Research Field:Theoretical and Applied Mechanics
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Mathematical Sciences
Author:Bassom, AP (Professor Andrew Bassom)
ID Code:108009
Year Published:1999
Web of Science® Times Cited:27
Deposited By:Mathematics and Physics
Deposited On:2016-04-04
Last Modified:2016-07-08
Downloads:0

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