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The importance of non-normal contributions to velocity gradient tensor dynamics for spatially developing, inhomogeneous, turbulent flows

journal contribution
posted on 21.11.2019 by P Beaumard, ORH Buxton, Chris Keylock
We investigate the properties of the velocity gradient tensor for spatially evolving turbulent flows (a near-wake, two axisymmetric jets and a planar mixing layer). Emphasis is placed on the study of the normal and non-normal parts of the tensor. Non-normality plays a greater role in the dynamics than is observed for HIT and does so for all spatial locations examined. This implies a greater role for viscosity or the deviatoric part of the pressure Hessian. Results for the wake flow, where we isolate the coherent part of the dynamics using a modal decomposition, clarifies how these competing
effects operate. Previous studies have shown the shape of the Q-R diagram (formed by the second and third invariants of the characteristic equation for the tensor) is approximately universal at small-scales for different flows. The non-normal dynamics are neglected in the Q-R approach but appear to differ significantly between flows.

History

School

  • Architecture, Building and Civil Engineering

Published in

Journal of Turbulence

Volume

20

Issue

9

Pages

577 - 598

Publisher

Taylor and Francis

Version

AM (Accepted Manuscript)

Rights holder

© Taylor and Francis

Publisher statement

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Turbulence on 29th Oct 2019, available online: https://doi.org/10.1080/14685248.2019.1685095

Acceptance date

15/10/2019

Publication date

2019-10-29

Copyright date

2019

eISSN

1468-5248

Language

en

Depositor

Prof Chris Keylock Deposit date: 20 November 2019

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