Navier-Stokes–based linear model for unstably stratified turbulent channel flows
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.
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.Attached Files
Published - PhysRevFluids.7.044601.pdf
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Additional details
- Eprint ID
- 114180
- Resolver ID
- CaltechAUTHORS:20220406-526254227
- Australian Research Council
- Created
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2022-04-06Created from EPrint's datestamp field
- Updated
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2022-04-06Created from EPrint's last_modified field
- Caltech groups
- GALCIT