Taming turbulent fronts by bending pipes

Barkley, Dwight

doi:10.1017/jfm.2019.340

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…In particular, we now discuss a mechanism by which splits could be suppressed compared to decays, and therefore a directed-percolation-type transition would be impossible. This could be relevant for slightly bent pipes [38,39]. In the slug-gap-split mechanism, the likelihood of the transition is the multiplication of that of the expansion stage, which increases with Re, and of the gap creation stage, which decreases with Re.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Mechanism for turbulence proliferation in subcritical flows

Frishman

Grafke

2022

Proc. R. Soc. A.

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The subcritical transition to turbulence, as occurs in pipe flow, is believed to generically be a phase transition in the directed percolation universality class. At its heart is a balance between the decay rate and proliferation rate of localized turbulent structures, called puffs in pipe flow. Here, we propose the first-ever dynamical mechanism for puff proliferation—the process by which a puff splits into two. In the first stage of our mechanism, a puff expands into a slug. In the second stage, a laminar gap is formed within the turbulent core. The notion of a split-edge state, mediating the transition from a single puff to a two-puff state, is introduced and its form is predicted. The role of fluctuations in the two stages of the transition, and how splits could be suppressed with increasing Reynolds number, are discussed. Using numerical simulations, the mechanism is validated within the stochastic Barkley model. Concrete predictions to test the proposed mechanism in pipe and other wall-bounded flows, and implications for the universality of the directed percolation picture, are discussed.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Mechanism for turbulence proliferation in subcritical flows

Frishman

Grafke

2022

Proc. R. Soc. A.

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show abstract

“…In particular, we now discuss a mechanism by which splits could be suppressed compared to decays, and therefore a directedpercolation-type transition would be impossible. This could be relevant for slightly bent pipes [36,37]. In the slug-gap-split mechanism the likelihood of the transition is the multiplication of that of the expansion stage, which increases with Re, and of the gap creation stage, which decreases with Re.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Dynamical mechanism of turbulence proliferation

Frishman¹,

Grafke²

2022

Preprint

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The subcritical transition to turbulence, as occurs in pipe flow, is believed to generically be a phase transition in the directed percolation universality class. At its heart is a balance between the decay rate and proliferation rate of localized turbulent structures, called puffs in pipe flow. Here we propose the first-ever dynamical mechanism for puff proliferation-the process by which a puff splits into two. In the first stage of our mechanism, a puff expands into a slug. In the second stage, a laminar gap is formed within the turbulent core. The notion of a split-edge state, mediating the transition from a single puff to a two puff state, is introduced and its form is predicted. The role of fluctuations in the two stages of the transition, and how splits could be suppressed with increasing Reynolds number, are discussed. Using numerical simulations, the mechanism is validated within the stochastic Barkley model. Concrete predictions to test the proposed mechanism in pipe and other wall bounded flows, and implications for the universality of the directed percolation picture, are discussed.

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“…More than 130 years after the seminal experiments by Osborne Reynolds, it is still a matter of debate [1,2]. Not only is it of scientific and engineering interest for the fluids community [3], but it also serves as a proving ground for the study of open complex dynamical systems and chaos theory. Many systems appearing in Nature present multiple solutions and exhibit complex routes to chaos, examples include the magnetic cycles of stellar dynamos [4], large-scale oscillations and bursts in tokamak plasmas [5], as well as a number of physico-chemical systems [6].…”

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confidence: 99%

Critical Point for Bifurcation Cascades and Featureless Turbulence

2020

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In this Letter we show that a bifurcation cascade and fully sustained turbulence can share the phase space of a fluid flow system, resulting in the presence of competing stable attractors. We analyse the toroidal pipe flow, which undergoes subcritical transition to turbulence at low pipe curvatures (pipe-to-torus diameter ratio) and supercritical transition at high curvatures, as was previously documented. We unveil an additional step in the bifurcation cascade and provide evidence that, in a narrow range of intermediate curvatures, its dynamics competes with that of sustained turbulence emerging through subcritical transition mechanisms.

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Taming turbulent fronts by bending pipes

Cited by 5 publications

References 18 publications

Mechanism for turbulence proliferation in subcritical flows

Mechanism for turbulence proliferation in subcritical flows

Dynamical mechanism of turbulence proliferation

Critical Point for Bifurcation Cascades and Featureless Turbulence

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