Phase transitions in anisotropic turbulence

Chaos An Interdisciplinary Journal of Nonlinear Science, Год журнала: 2024, Номер 34(12)

Опубликована: Дек. 1, 2024

Turbulence is a widely observed state of fluid flows, characterized by complex, nonlinear interactions between motions across broad spectrum length and time scales. While turbulence ubiquitous, from teacups to planetary atmospheres, oceans, stars, its manifestations can vary considerably different physical systems. For instance, three-dimensional turbulent flows display forward energy cascade large small scales, while in two-dimensional turbulence, cascades In given system, transition such disparate regimes occur when control parameter reaches critical value. The behavior close points, which separate qualitatively distinct phases has been found be unexpectedly rich. Here, we survey recent findings on transitions highly anisotropic including thin layers under the influence rapid rotation. We also review work induced fluctuations, as random reversals large-scale vortices jets, among others. relevance these results their ramifications for future investigations are discussed.

Язык: Английский

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Functional renormalisation group for turbulence

Journal of Fluid Mechanics, Год журнала: 2022, Номер 950

Опубликована: Окт. 24, 2022

Turbulence is a complex nonlinear and multi-scale phenomenon. Although the fundamental underlying equations, Navier–Stokes have been known for two centuries, it remains extremely challenging to extract from them statistical properties of turbulence. Therefore, practical purposes, sustained effort has devoted obtaining an effective description turbulence, that we may call turbulence modelling, or theory In this respect, renormalisation group (RG) appears as tool choice, since precisely designed provide theories equations by performing in systematic way average over fluctuations. However, suitable framework RG, allowing particular non-perturbative approximations, missing, which thwarted RG applications long time. This provided modern formulation called functional (FRG). The use FRG enabled important progress theoretical understanding homogeneous isotropic major one rigorous derivation, analytical expression any Eulerian multi-point multi-time correlation function, exact limit large wavenumbers. We propose JFM Perspectives article survey method basic introduction emphasise how field-theoretical allows systematically profoundly exploit symmetries. stress enables describe fully developed forced at scales, was not accessible perturbative means. show yields energy spectrum second-order structure function with accurate estimates related constants, also behaviour near-dissipative range. Finally, expound derivation spatio-temporal $n$ -point functions, largely illustrate these results through analysis data experiments direct numerical simulations.

Язык: Английский

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A two-experiment finite similitude approach to experimental fluid mechanics

European Journal of Mechanics - B/Fluids, Год журнала: 2023, Номер 99, С. 43 - 56

Опубликована: Янв. 17, 2023

Fluid dynamics experimentation at scale provides an important means of investigation that is presently underpinned by dimensional analysis and computational fluid (CFD). Unfortunately, despite the obvious success this twin approach, no solution if effects are prevalent CFD offers reduced practical advantage in absence a theory links information across scaled experiments. This issue addressed paper with introduction new approach to founded on finite similitude. Finite similitude metaphysical concept space scaling, where experimental apparatuses, facilities, prototypes, systems, wind tunnels etc., contraction or expansion. There exists contract expand but what possible mathematical description scaling its impact governing physics, so providing for comparison systems real-world behaviours. examines adaptation finite-similitude theory, two experiments involved second-order version applied. All previous work has been limited zeroth first-order applications, case dynamics, second order shown necessary capture more accurately convective terms. It demonstrated (designed using theory) able represent behaviours full hitherto would have deemed impossible traditional analysis. Numerical analytical studies gravity impacted flows trialled illustrate benefits percentage errors from double single digits.

Язык: Английский

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Cascades and Kolmogorov's lognormal scaling in two-dimensional bacterial turbulence

Physics of Fluids, Год журнала: 2024, Номер 36(6)

Опубликована: Июнь 1, 2024

Collective movements of bacteria exhibit a remarkable pattern turbulence-like vortices, in which the Richardson cascade plays an important role. In this work, we examine energy and enstrophy cascades their associated lognormal statistics using experimental velocity field data. The coherent structure observed on large scale is due to presence inverse cascade, while kinetic dissipated at all scales, since these active occur below fluid viscosity scale. forward occurs with injection scales may be represented by other nonlinear interactions that are not captured existing Furthermore, for both dissipation fields verified accordance Kolmogorov 1962 refined theory turbulence. Their scaling exponents can well described formula intermittency parameters comparable those three-dimensional hydrodynamic joint analysis multifractal measures rate follows ellipse model from statistics. Our results confirm coexistence correction system. An diagram summarized describe two-dimensional bacterial work provides example active-flow benchmark.

Язык: Английский

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GPU-enabled extreme-scale turbulence simulations: Fourier pseudo-spectral algorithms at the Exascale using OpenMP offloading

Computer Physics Communications, Год журнала: 2024, Номер 306, С. 109364 - 109364

Опубликована: Сен. 5, 2024

Язык: Английский

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Hidden turbulence in van Gogh's The Starry Night

Physics of Fluids, Год журнала: 2024, Номер 36(9)

Опубликована: Сен. 1, 2024

Turbulent skies have often inspired artists, particularly in the iconic swirls of Vincent van Gogh's The Starry Night. For an extended period, debate has raged over whether flow pattern this masterpiece adheres to Kolmogorov's theory turbulence. In contrast previous studies that examined only part painting, all and whirls/eddies painting are taken into account work, following Richardson–Kolmogorov's cascade picture Consequently, luminance's Fourier power spectrum spontaneously exhibits a characteristic −5/3 Kolmogorov-like power-law. This result suggests Gogh had very careful observation real flows, so not sizes Night but also their relative distances intensity follow physical law governs turbulent flows. Moreover, “–1”-like power-law persists below scales smallest whirls, hinting at Batchelor-type scalar turbulence with high Schmidt number. Our study, thus, unveils hidden captured within

Язык: Английский

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Kinetic energy spectrum and transfer within the near-dissipation range of compressible isotropic turbulence

Physics of Fluids, Год журнала: 2025, Номер 37(1)

Опубликована: Янв. 1, 2025

The analysis of kinetic energy spectrum and dissipation mechanisms plays a crucial role in both theoretical examination real-world implementations within compressible turbulent flows. previous works the near-dissipation range are conducted framework incompressible flow dynamics. We investigate transfer isotropic flows via highly resolved direct numerical simulations with different Mach numbers (Mt). found that flows, model is significantly influenced by number, more pronounced tail as number increases. Within range, there exist strong local spatial fluctuations flux increase grid resolution. viscous can be decomposed into solenoidal dilatational components, its component leads to stronger intermittency range. Besides, high also dissipation, which serves an alternative factor for uncovered provides foundation prediction intense events development modelings.

Язык: Английский

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Sound-vortex conversion on droplets: Kinematic model of sound activated vortices

Physics of Fluids, Год журнала: 2025, Номер 37(1)

Опубликована: Янв. 1, 2025

The rapid pace of urbanization across the globe has led to proliferation various urban infrastructure. They generate aerodynamic noise, posing significant challenges planning and residents' comfort. Despite Lighthill's mathematical analogy, current noise control applications rely heavily on wind tunnel tests computer simulations. Physical mechanisms behind aeroacoustic have yet be validated elucidated experimentally. This work observed geometry sound-activated vortices determined their streamline velocity distribution. theoretical results are consistent with experimental observations, offering a kinematic model for sound activated vortices. experimentally improves understanding provides development strategies.

Язык: Английский

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Analytical developments for turbulent flows subjected to strong temperature gradients

International Communications in Heat and Mass Transfer, Год журнала: 2025, Номер 162, С. 108550 - 108550

Опубликована: Янв. 14, 2025

Язык: Английский

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Calculating spectra by sequential filtering

Journal of Renewable and Sustainable Energy, Год журнала: 2025, Номер 17(1)

Опубликована: Янв. 1, 2025

We expand on the method of sequential filtering for calculating spectra inhomogeneous fields. Sadek and Aluie [Phys. Rev. Fluids 3, 124610 (2018)] showed that kernel has to have at least p vanishing moments extract a power-law spectrum k−α with α<p+2 by low-pass filtering. Here, we show high-pass allows extracting steeper α<2p+3 using same pth order kernel. For example, field is shallower than k−5 can be extracted any first-order such as Gaussian or top-hat. Finally, demonstrate how second-order structure function fails capture spectral peaks because it cannot detect scaling too shallow.

Язык: Английский

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