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.
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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 | ||||||||||
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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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