Linear instability of turbulent channel flow

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 instab...

Full description

Saved in:
Bibliographic Details
Published in:arXiv.org 2022-09
Main Authors: Kashyap, Pavan V, Duguet, Yohann, Dauchot, Olivier
Format: Article
Language:English
Subjects:
Channel flow
Flow stability
Fluid dynamics
Laminar flow
Mathematical models
Modulation
Shear flow
Turbulent flow
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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 wavevector of the modulation at onset.
ISSN:2331-8422
DOI:10.48550/arxiv.2205.05652