Do extreme events trigger turbulence decay? – a numerical study of turbulence decay time in pipe flows

Nemoto, Takahiro; Alexakis, Alexandros

doi:10.1017/jfm.2020.1150

Cited by 11 publications

(14 citation statements)

References 38 publications

(69 reference statements)

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“…The length Lz=100 of our tilted domain corresponds to an inter-band distance above which a band is considered as isolated, while the domain width Lx=6.6 is used because it corresponds to the natural spacing of streaks in channel flow in a 24∘ box [6,31]. For puffs in pipe flow, which are similar in many respects to the isolated bands considered here, Nemoto & Alexakis [21] conducted extensive computations showing that domain length had some effect on mean decay timescales, with L=50 and L=100 giving quantitatively different, but qualitatively similar results. Domain length is expected to have a quantitative effect on the splitting timescale; our domain length Lz=100 has been selected as a compromise between accuracy and computational cost.…”

Section: Methodsmentioning

confidence: 99%

“…In a study of the decay of turbulent puffs in pipe flow, Nemoto & Alexakis [21] found that the maximal vorticity over the domain followed a Fréchet distribution, a member of the Fisher–Tippett family. Moreover, they found that the parameters of this distribution depend linearly on Re over a range of 75 in Re near the critical value Rec.…”

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

“…We can now apply the Nemoto & Alexakis approach [21] to our decay and splitting data. The essential idea is to scale the CDFs and obtain forms that separate into approximately Re-independent portions and Re-dependent portions that can be fit to Fisher–Tippett distributions.…”

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

“…The first equality can be understood as follows [21]. Consider estimating τd by MC simulation with Nnormaldecay independent realizations of decay events.…”

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

“…The interpretation of these results comes from the mechanism proposed by Goldenfeld et al . [19] and subsequently refined by Nemoto & Alexakis [20,21]. We focus on the decay case, but similar statements apply to the splitting case.…”

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

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Extreme events in transitional turbulence

Gomé

Tuckerman

Barkley

2022

Phil. Trans. R. Soc. A.

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Transitional localized turbulence in shear flows is known to either decay to an absorbing laminar state or to proliferate via splitting. The average passage times from one state to the other depend super-exponentially on the Reynolds number and lead to a crossing Reynolds number above which proliferation is more likely than decay. In this paper, we apply a rare-event algorithm, Adaptative Multilevel Splitting, to the deterministic Navier–Stokes equations to study transition paths and estimate large passage times in channel flow more efficiently than direct simulations. We establish a connection with extreme value distributions and show that transition between states is mediated by a regime that is self-similar with the Reynolds number. The super-exponential variation of the passage times is linked to the Reynolds number dependence of the parameters of the extreme value distribution. Finally, motivated by instantons from Large Deviation theory, we show that decay or splitting events approach a most-probable pathway. This article is part of the theme issue ‘Mathematical problems in physical fluid dynamics (part 2)’.

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Section: Methodsmentioning

confidence: 99%

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

“…The first equality can be understood as follows [21]. Consider estimating τd by MC simulation with Nnormaldecay independent realizations of decay events.…”

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

Section: Extreme Value Description Of Decay and Splitting Trajectoriesmentioning

confidence: 99%

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Extreme events in transitional turbulence

Gomé

Tuckerman

Barkley

2022

Phil. Trans. R. Soc. A.

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Wall-Bounded Turbulent Flows

Kollmann

2024

Navier-Stokes Turbulence

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Bistability of the large-scale dynamics in quasi-two-dimensional turbulence

2022

Self Cite

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In many geophysical and astrophysical flows, suppression of fluctuations along one direction of the flow drives a quasi-two-dimensional upscale flux of kinetic energy, leading to the formation of strong vortex condensates at the largest scales. Recent studies have shown that the transition towards this condensate state is hysteretic, giving rise to a limited bistable range in which both the condensate state as well as the regular three-dimensional state can exist at the same parameter values. In this work, we use direct numerical simulations of thin-layer flow to investigate whether this bistable range survives as the domain size and turbulence intensity are increased. By studying the time scales at which rare transitions occur from one state into the other, we find that the bistable range grows as the box size and/or Reynolds number $Re$ are increased, showing that the bistability is neither a finite-size nor a finite- $Re$ effect. We furthermore predict a cross-over from a bimodal regime at low box size, low $Re$ to a regime of pure hysteresis at high box size, high $Re$ , in which any transition from one state to the other is prohibited at any finite time scale.

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Do extreme events trigger turbulence decay? – a numerical study of turbulence decay time in pipe flows

Abstract: Abstract

Cited by 11 publications

References 38 publications

Extreme events in transitional turbulence

Extreme events in transitional turbulence

Wall-Bounded Turbulent Flows

Bistability of the large-scale dynamics in quasi-two-dimensional turbulence

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