Kashyap, PV and Duguet, Y and Dauchot, O (2022) Linear Instability of Turbulent Channel Flow. In: Physical Review Letters, 129 (24).
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Abstract
Laminar-turbulent pattern formation is a distinctive feature of the intermittency regime in subcritical plane shear flows. By performing extensive numerical simulations of the plane channel flow, we show that the pattern emerges from a spatial modulation of the turbulent flow, due to a linear instability. We sample over many realizations the linear response of the fluctuating turbulent field to a temporal impulse, in the regime where the turbulent flow is stable, just before the onset of the instability. The dispersion relation is constructed from the ensemble-averaged relaxation rates. As the instability threshold is approached, the relaxation rate of the least damped modes eventually reaches zero. The method allows, despite the presence of turbulent fluctuations and without any closure model, for an accurate estimation of the wave vector of the modulation at onset. © 2022 American Physical Society.
| Item Type: | Journal Article |
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| Publication: | Physical Review Letters |
| Publisher: | American Physical Society |
| Additional Information: | The copyright for this article belongs to the Authors. |
| Keywords: | Channel flow; Shear flow; Turbulent flow, Intermittency; Linear instabilities; Linear response; Pattern formation; Plane channel flow; Plane shear flows; Relaxation rates; Spatial modulations; Turbulent channel flows; Turbulent patterns, Stability |
| Department/Centre: | Division of Mechanical Sciences > Mechanical Engineering |
| Date Deposited: | 17 Jan 2023 09:38 |
| Last Modified: | 17 Jan 2023 09:38 |
| URI: | https://eprints.iisc.ac.in/id/eprint/79185 |
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