Direct Path from Turbulence to Time-Periodic Solutions

Chaitanya, Paranjape,; Gökhan, Yalnız,; Duguet, Yohann; Budanur, Nazmi Burak; Hof, Björn

doi:10.1103/physrevlett.131.034002

Cited by 4 publications

(1 citation statement)

References 43 publications

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“…For pipe flow, it has been found that the ECS originates in saddle-node bifurcations at Re D down to around 400 [79]. The TWs consist of a certain number of azimuthally and radially separated streaks; for example, threefold azimuthal symmetry: six outer (high speed) streaks and three inner (low speed) streaks.…”

Section: Dynamical Systems Viewpointmentioning

confidence: 99%

The Chimera Revisited: Wall- and Magnetically-Bounded Turbulent Flows

Basse

2024

Fluids

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Section: Dynamical Systems Viewpointmentioning

confidence: 99%

The Chimera Revisited: Wall- and Magnetically-Bounded Turbulent Flows

Basse

2024

Fluids

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Chaotic edge regimes in magnetohydrodynamic channel flow: An alternative path towards the tipping point

Brynjell-Rahkola,

Duguet,

Boeck

2024

Phys. Rev. Research

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The effect of an imposed magnetic field on the flow of an electrically conducting fluid in a channel geometry is investigated numerically using high-performance temporal simulations. For the strongest spanwise magnetic fields considered, the turbulent state appears metastable, which makes the determination of the associated tipping point arduous. As an alternative, edge states, i.e., unstable states located on the state space boundary between the laminar and the turbulent basin of attraction, are investigated in detail. Their continuation smoothly leads to the tipping point where they are expected to collide with the turbulent dynamics. As the magnetic field intensity is raised, edge states become, on average, more energetic and more unstable, while their fluctuations become more chaotic, less predictable, and less symmetric. Nevertheless, their continuation allows one to accurately determine the value of the tipping point beyond which the laminar state becomes the only attractor. Published by the American Physical Society 2024

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From laminar to chaotic flow via stochastic resonance in viscoelastic channel flow

Li,

Steinberg

2024

Phys. Rev. Research

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Recent research indicates that low-inertia viscoelastic channel flow experiences supercritical nonnormal mode elastic instability from laminar to sustained chaotic flow due to finite-size perturbations. The challenge of this paper is to elucidate a realization of such a pathway when the intensity of the elastic wave is too low to amplify vortex fluctuations above the instability onset. The study identifies two subregions in the transition flow regime at Weissenberg number Wi>Wic, the instability onset. In the lower subregion at Wic≤Wi≤300, we discover periodic spikes in the streamwise velocity time series u(t) that appear in the chaotic power spectrum as low-frequency, high-intensity peaks resembling stochastic resonance (SR). In contrast, the spanwise velocity power spectrum, Ew, remains flat and with low-intensity, noisy, and broad elastic wave peaks. The spikes significantly distort the probability density function of u and initiate and amplify random streaks and wall-normal vorticity fluctuations. The condition for the SR emergence is similar to that of a dynamical system where the presence of a chaotic attractor, limit cycle, and external white noise are necessary. This similarity is confirmed by presenting a phase portrait in two subregions of the transition regime. In the upper subregion at Wi>400, the periodic spikes disappear and Ew becomes chaotic with a large intensity elastic wave sufficient to self-organize and synchronize the streaks into cycles and to amplify the wall normal vorticity, according to a recently proposed mechanism of vortex-wave interactions. Published by the American Physical Society 2024

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Direct Path from Turbulence to Time-Periodic Solutions

Cited by 4 publications

References 43 publications

The Chimera Revisited: Wall- and Magnetically-Bounded Turbulent Flows

The Chimera Revisited: Wall- and Magnetically-Bounded Turbulent Flows

Chaotic edge regimes in magnetohydrodynamic channel flow: An alternative path towards the tipping point

From laminar to chaotic flow via stochastic resonance in viscoelastic channel flow

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