Trigger turbulent bands directly at low Reynolds numbers in channel flow using a moving-force technique

Abstract

We show a method, for direct numerical simulations, to trigger and maintain turbulent bands directly at low Reynolds numbers in channel flow. The key is to impose a moving localised force which induces a local flow with sufficiently strong inflectional instability. With the method, we can trigger and maintain turbulent bands at Reynolds numbers down to $Re\simeq 500$. More importantly, we can generate any band patterns with desired relative position and orientation. The usual perturbation approach resorts to turbulent fields simulated at higher Reynolds numbers, random noise, or localised vortical perturbation, which neither assures a successful generation of bands at low Reynolds numbers nor offers a control on the orientation of the generated bands. A precise control on the position and orientation of turbulent bands is important for the investigation of all possible types of band interaction and for understanding the transition in channel flow at low Reynolds numbers.

arXiv comment22 pages, 16 figures

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Cited by in corpus (4)

• Structured input-output analysis of transitional wall-bounded flows
• Linear instability of turbulent channel flow
• Linear and nonlinear optimal growth mechanisms for generating turbulent bands
• Size-dependent transient nature of localized turbulence in transitional channel flow