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Navier-Stokes–based linear model for unstably stratified turbulent channel flows

Madhusudanan, Anagha and Illingworth, Simon J. and Marusic, Ivan and Chung, Daniel (2022) Navier-Stokes–based linear model for unstably stratified turbulent channel flows. Physical Review Fluids, 7 (4). Art. No. 044601. ISSN 2469-990X. doi:10.1103/physrevfluids.7.044601. https://resolver.caltech.edu/CaltechAUTHORS:20220406-526254227

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Abstract

We use the linearized Navier-Stokes equations to study the large-scale flow structures in unstably stratified turbulent channel flows. The impulse response of the linear operator at bulk Richardson numbers from Ri_b = 0.001 to Ri_b = 1.0 are considered, corresponding to the increasing influence of buoyancy relative to shear. We compare the streamwise-constant flow structures predicted by the linear model to the quasistreamwise rolls that emerge with increasing Ri_b in direct numerical simulations (DNSs) [e.g., Pirozzoli et al., J. Fluid Mech. 821, 482 (2017)]. The linearized Navier-Stokes equations augmented with eddy-viscosity and eddy-diffusivity capture the emergence of the quasistreamwise rolls well. With increasing Ri_b, the temperature fluctuations of the streamwise-constant flow structures transition from having a peak in intensity at the channel centerline to having two peaks, one at each wall, consistent with DNS.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1103/PhysRevFluids.7.044601DOIArticle
ORCID:
AuthorORCID
Madhusudanan, Anagha0000-0003-3461-3772
Illingworth, Simon J.0000-0002-7545-9786
Marusic, Ivan0000-0003-2700-8435
Chung, Daniel0000-0003-3732-364X
Additional Information:© 2022 American Physical Society. (Received 10 September 2021; accepted 25 February 2022; published 6 April 2022) The authors gratefully acknowledge the financial support of the Australian Research Council. We also thank Prof. Sergio Pirozzoli for providing the DNS data of Pirozzoli et al. [25] and Dr. Sean Symon for helpful discussions regarding this work.
Group:GALCIT
Funders:
Funding AgencyGrant Number
Australian Research CouncilUNSPECIFIED
Issue or Number:4
DOI:10.1103/physrevfluids.7.044601
Record Number:CaltechAUTHORS:20220406-526254227
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220406-526254227
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114180
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:06 Apr 2022 13:36
Last Modified:06 Apr 2022 23:48

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