The University of Southampton
University of Southampton Institutional Repository

Amplification of enstrophy in the far field of an axisymmetric turbulent jet

Buxton, O.R.H. and Ganapathisubramani, B. (2010) Amplification of enstrophy in the far field of an axisymmetric turbulent jet Journal of Fluid Mechanics, 651, pp. 483-502. (doi:10.1017/S0022112009993892).

Record type: Article


The amplification of enstrophy is explored using cinematographic stereoscopic particle image velocimetry data. The enstrophy production rate is investigated by observation of the statistical tendency of the vorticity vector (?) to align with the eigenvectors of the rate of strain tensor (ei). Previous studies have shown that ? preferentially aligns with the intermediate strain-rate eigenvector (e2) and is arbitrarily aligned with the extensive strain-rate eigenvector (e1). This study shows, however, that the nature of enstrophy amplification, whether it is positive (enstrophy production) or negative (enstrophy destruction), is dictated by the alignment between ? and e1. Parallel alignment leads to enstrophy production (?iSij?j>0), whereas perpendicular alignment leads to enstrophy destruction (?iSij?j<0). In this way, the arbitrary alignment between ? and e1 is the summation of the effects of enstrophy producing and enstrophy destroying regions. The structure of enstrophy production is also examined with regards to the intermediate strain-rate eigenvalue, s2. Enstrophy producing regions are found to be topologically ‘sheet-forming’, due to an extensive (positive) value of s2 in these regions, whereas enstrophy destroying regions are found to be ‘spotty’. Strong enstrophy producing regions are observed to occur in areas of strong local swirling as well as in highly dissipative regions. Instantaneous visualizations, produced from the volume of data created by Taylor's hypothesis, reveal that these ‘sheet-like’ strong enstrophy producing regions encompass the high enstrophy, strongly swirling ‘worms’. These ‘worms’ induce high local strain fields leading to the formation of dissipation ‘sheets’, thereby revealing enstrophy production to be a complex interaction between rotation and strain – the skew-symmetric and symmetric components of the velocity gradient tensor, respectively

PDF Buxton2010.pdf - Version of Record
Restricted to Repository staff only
Download (1MB)

More information

Published date: March 2010
Organisations: Aerodynamics & Flight Mechanics


Local EPrints ID: 179145
ISSN: 0022-1120
PURE UUID: 43006a0b-2eec-4b07-82b5-6f30e07dd9fb
ORCID for B. Ganapathisubramani: ORCID iD

Catalogue record

Date deposited: 08 Apr 2011 09:17
Last modified: 18 Jul 2017 12:03

Export record


Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton:

ePrints Soton supports OAI 2.0 with a base URL of

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.