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Lift-up, Kelvin-Helmholtz and Orr mechanisms in turbulent jets

Pickering, Ethan and Rigas, Georgios and Nogueira, Petrônio A. S. and Cavalieri, André V. G. and Schmidt, Oliver T. and Colonius, Tim (2020) Lift-up, Kelvin-Helmholtz and Orr mechanisms in turbulent jets. Journal of Fluid Mechanics, 896 . Art. No. A2. ISSN 0022-1120.

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Three amplification mechanisms present in turbulent jets, namely lift-up, Kelvin–Helmholtz and Orr, are characterized via global resolvent analysis and spectral proper orthogonal decomposition (SPOD) over a range of Mach numbers. The lift-up mechanism was recently identified in turbulent jets via local analysis by Nogueira et al. (J. Fluid Mech., vol. 873, 2019, pp. 211–237) at low Strouhal number ( St ) and non-zero azimuthal wavenumbers ( m ). In these limits, a global SPOD analysis of data from high-fidelity simulations reveals streamwise vortices and streaks similar to those found in turbulent wall-bounded flows. These structures are in qualitative agreement with the global resolvent analysis, which shows that they are a response to upstream forcing of streamwise vorticity near the nozzle exit. Analysis of mode shapes, component-wise amplitudes and sensitivity analysis distinguishes the three mechanisms and the regions of frequency–wavenumber space where each dominates, finding lift-up to be dominant as St/m→0 . Finally, SPOD and resolvent analyses of localized regions show that the lift-up mechanism is present throughout the jet, with a dominant azimuthal wavenumber inversely proportional to streamwise distance from the nozzle, with streaks of azimuthal wavenumber exceeding five near the nozzle, and wavenumbers one and two most energetic far downstream of the potential core.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Pickering, Ethan0000-0002-4485-6359
Rigas, Georgios0000-0001-6692-6437
Cavalieri, André V. G.0000-0003-4283-0232
Schmidt, Oliver T.0000-0002-7097-0235
Colonius, Tim0000-0003-0326-3909
Additional Information:© 2020 The Author(s). Published by Cambridge University Press. Received 18 September 2019; revised 11 February 2020; accepted 14 April 2020. This research was supported by a grant from the Office of Naval Research (grant no. N00014-16-1-2445) with Dr S. Martens as program manager. E.P. was supported by the Department of Defense (DoD) through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program. The LES study was performed at Cascade Technologies, with support from ONR and NAVAIR SBIR project, under the supervision of Dr J. T. Spyropoulos. The main LES calculations were carried out on DoD HPC systems in ERDC DSRC. The authors report no conflict of interest.
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-16-1-2445
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
Subject Keywords:jets, compressible turbulence, high-speed flow
Record Number:CaltechAUTHORS:20200122-091643948
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Official Citation:Pickering, E., Rigas, G., Nogueira, P., Cavalieri, A., Schmidt, O., & Colonius, T. (2020). Lift-up, Kelvin–Helmholtz and Orr mechanisms in turbulent jets. Journal of Fluid Mechanics, 896, A2. doi:10.1017/jfm.2020.301
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100830
Deposited By: Tony Diaz
Deposited On:23 Jan 2020 00:21
Last Modified:11 Jun 2020 17:47

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