Global energy spectrum of the general oceanic circulation

Nature Communications, Год журнала: 2022, Номер 13(1)

Опубликована: Сен. 9, 2022

Advent of satellite altimetry brought into focus the pervasiveness mesoscale eddies [Formula: see text] km in size, which are ocean's analogue weather systems and often regarded as spectral peak kinetic energy (KE). Yet, understanding spatial scales has been derived mostly from Fourier analysis small "representative" regions that cannot capture vast dynamic range at planetary scales. Here, we use a coarse-graining method to analyze much larger than what had possible before. Spectra spanning over three decades length-scales reveal Antarctic Circumpolar Current global extra-tropical circulation, ≈ 104 km, previously unobserved power-law scaling 103 km. A smaller exists 300 associated with mesoscales, which, due their wider spread wavenumber space, account for more 50% resolved surface KE globally. Seasonal cycles exhibit characteristic lag-time 40 days per octave such both hemispheres, 102 peaks spring while late summer. These results provide new window multiscale oceanic circulation within Earth's climate system, including largest

Язык: Английский

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Compressibility effects on mixing layer in Rayleigh–Taylor turbulence

Physica D Nonlinear Phenomena, Год журнала: 2025, Номер unknown, С. 134643 - 134643

Опубликована: Март 1, 2025

Язык: Английский

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Spatio‐Temporal Coarse‐Graining Decomposition of the Global Ocean Geostrophic Kinetic Energy

Journal of Advances in Modeling Earth Systems, Год журнала: 2023, Номер 15(6)

Опубликована: Июнь 1, 2023

Abstract We expand on a recent determination of the first global energy spectrum ocean's surface geostrophic circulation (Storer et al., 2022, https://doi.org/10.1038/s41467-022-33031-3 ) using coarse‐graining (CG) method. compare spectra from CG to those spherical harmonics by treating land in manner consistent with boundary conditions. While two methods yield qualitatively domain‐averaged results, are too noisy at gyre‐scales (>1,000 km). More importantly, inherently and cannot provide local information connecting scales currents geographically. shows that extra‐tropics mesoscales (100–500 km) have root‐mean‐square (rms) velocity ∼15 cm/s, which increases ∼30–40 cm/s locally Gulf Stream Kuroshio ∼16–28 ACC. There is notable hemispheric asymmetry mesoscale energy‐per‐area, higher north due continental boundaries. estimate ≈25%–50% total smaller than 100 km, un(der)‐resolved pre‐SWOT satellite products. Spectra time‐mean show most its (up 70%) resides stationary eddies characteristic (<500 This highlights preponderance “standing” small‐scale structures ocean temporally coherent forcing By space time, we compute spatio‐temporal AVISO NEMO. These every length‐scale evolves over wide range time‐scales peak ≈200 km ≈2–3 weeks.

Язык: Английский

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Particle acceleration by magnetic Rayleigh-Taylor instability: Mechanism for flares in black hole accretion flows

Physical Review Research, Год журнала: 2023, Номер 5(4)

Опубликована: Окт. 9, 2023

This article uses magnetic Rayleigh-Taylor instability in relativistic collisionless plasma as an example of astrophysical process for nonthermal particle acceleration, and uncover the onset large-scale plumes formed by accumulation small ones via particle-in-cell simulations. is posed a potential mechanism flares.

Язык: Английский

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Bubble re-acceleration behaviours in compressible Rayleigh–Taylor instability with isothermal stratification

Journal of Fluid Mechanics, Год журнала: 2023, Номер 954

Опубликована: Янв. 3, 2023

The highly nonlinear evolution of the single-mode stratified compressible Rayleigh–Taylor instability (RTI) is investigated via direct numerical simulation over a range Atwood numbers ( $A_T=0.1$ – $0.9$ ) and Mach $Ma=0.1$ $0.7$ for characterising isothermal background stratification. After potential stage, it found that bubble accelerated to velocity which well above saturation value predicted in flow model. Unlike re-acceleration behaviour quasi-incompressible RTI with uniform density, characteristics are driven by not only vorticity accumulation inside but also compressibility resulting from Specifically, case strong stratification high $A_T$ , dominates characters. To model effect compressibility, we propose novel reliably describe behaviours RTI, introducing dilatation into classical takes account accumulation.

Язык: Английский

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Mixing and inter-scale energy transfer in Richtmyer–Meshkov turbulence

Journal of Fluid Mechanics, Год журнала: 2024, Номер 984

Опубликована: Апрель 8, 2024

This work investigates the compressible turbulence induced by Richtmyer–Meshkov (RM) instability using high-resolution Navier–Stokes simulations. Special attention is paid to characteristics of RM including mixing width growth, turbulent kinetic energy (TKE) decay, degree, inhomogeneity and anisotropy. Three distinct initial perturbation spectra are designed at interface reveal condition imprint on turbulence. Results show that cases with large-scale perturbations present a stronger statistical also quicker growth width, whereas small-scale faster TKE greater level, higher isotropy homogeneity. A thorough analysis inter-scale transfer in presented coarse-graining approach exposes two subfilter-scale (SFS) fluxes (i.e. deformation baropycnal work). strong correlation between nonlinear model ( Fluids , 4 (2), 2019) simulation results confirmed for first time, demonstrating its potential modelling Two primary mechanisms (the straining baroclinic generation processes) explored this model. The evolutions SFS exhibit behaviours various filter scales, different flow regions under motions (strain rotation). It found all three share common dynamics, which important

Язык: Английский

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Direct numerical simulations of three-component Rayleigh–Taylor mixing and an improved model for multicomponent reacting mixtures

Journal of Fluid Mechanics, Год журнала: 2024, Номер 999

Опубликована: Ноя. 21, 2024

We present direct numerical simulations of a three-layer Rayleigh–Taylor instability (RTI) problem with configuration based on the experiments Suchandra & Ranjan ( J. Fluid Mech. , vol. 974, 2023, A35) and Jacobs Dalziel 542, 2005, pp. 251–279). The consists layer light fluid between two layers heavy an Atwood number 0.3. These are first validated through comparison available experimental data. then utilized to analyse statistics in this three-component flow. First, length scales examined utilizing spectra two-point spatial correlations velocity species concentration fluctuations. Next, joint probability density functions (p.d.f.s) compared against several model p.d.f.s representing generalizations bivariate beta distribution. Notably, do not appear be accurately described by Dirichlet distribution, indicating marginal distributions conform Finally, similarity mixing found inertial confinement fusion (ICF) applications is exploited develop validate improved for impact multicomponent thermonuclear (TN) reaction rates. A single time instant from chosen TN burn calculation under hypothetical assumption ICF materials temperatures. Total output second prediction model. new predict rates both premixed non-premixed configurations.

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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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&lt;p+2 by low-pass filtering. Here, we show high-pass allows extracting steeper α&lt;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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The role of double‐layer vortex rings with the local swirl in the rapid transition to turbulent flows in Richtmyer–Meshkov instability with reshock

Journal of Fluid Mechanics, Год журнала: 2025, Номер 1003

Опубликована: Янв. 24, 2025

In this paper, we study the rapid transition in Richtmyer–Meshkov instability (RMI) with reshock through three-dimensional double-layer swirling vortex rings. The RMI has an essential influence on evolution of supernovas and ignition inertial confinement fusion, which been confirmed numerical simulations experiments shock-tube high-energy-density facilities over past few years. Vortex to dominate late-time nonlinear development perturbed interface. However, studies have investigated characteristics interactions among structures during turbulent flows. coexistence co-rotating counter-rotating vortices is hypothesized induce successive large-scale strain fields, are main driving sources for development. effect reflected presence local motion azimuthal direction, it decreases translation velocity a ring. Large-, middle- small-scale fields employed describe process reshock, e.g. vorticity deposited by formation vortices, iterative cascade under amplification viscous dissipation internal energy. This provides theoretical suggestions designing practical applications, such as estimation hydrodynamic mixing acceleration phase fusion.

Язык: Английский

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