Calculating spectra by sequential filtering

Journal of Renewable and Sustainable Energy, Journal Year: 2025, Volume and Issue: 17(1)

Published: Jan. 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.

Language: Английский

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Dynamics and Thermodynamics of the Boussinesq North Atlantic Eddy Kinetic Energy Spectral Budget

Journal of Advances in Modeling Earth Systems, Journal Year: 2025, Volume and Issue: 17(4)

Published: April 1, 2025

Abstract Statistical characterization of oceanic flows has been a long standing issue; such information is invaluable for formulating hypotheses and testing them. It also allows us to understand the energy pathways within ocean, which highly turbulent. Here, we apply wavelet approach wavenumber spectral analysis, recently proved be beneficial in quantifying spatially heterogeneous anisotropic nature flows. Utilizing an eddy‐rich ensemble simulation North Atlantic, are able examine transfers eddy kinetic (EKE) effect potential energy, here defined via dynamic enthalpy, on EKE budget. We find that vertical advection modulates up‐ down‐scale direction strength flux throughout Atlantic domain. The buoyancy tends small below mixed layer, suggesting flow largely adiabatic. In maintaining this adiabatic nature, enthalpy practical salinity tend partially compensate temperature; partial cancellation between temperature similar thermodynamic spice variable.

Language: Английский

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Scale interactions and anisotropy in Rayleigh–Taylor turbulence

Journal of Fluid Mechanics, Journal Year: 2021, Volume and Issue: 930

Published: Nov. 16, 2021

We study energy scale transfer in Rayleigh–Taylor (RT) flows by coarse graining physical space without Fourier transforms, allowing analysis along the vertical direction. Two processes are responsible for kinetic flux across scales: baropycnal work $\varLambda$ , due to large-scale pressure gradients acting on small scales of density and velocity; deformation $\varPi$ multiscale velocity. Our coarse-graining shows how these fluxes exhibit self-similar evolution that is quadratic-in-time, similar RT mixing layer. find a conduit potential energy, transferring non-locally from largest smaller inertial range where takes over. In three dimensions, continues persistent cascade scales, whereas two dimensions rechannels back larger despite lack vorticity conservation two-dimensional (2-D) variable flows. This gives rise positive feedback loop 2-D (absent dimensions) which layer growth associated release enhanced relative 3-D RT, explaining oft-observed $\alpha$ values simulations. Despite higher bulk levels weaker than dimensions. Moreover, net upscale tends isotropize flow, stark contrast findings indicate absence three-dimensional as often claimed; bubbles spikes not ‘mergers’ but solely .

Language: Английский

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

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(1)

Published: Jan. 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.

Language: 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, Journal Year: 2025, Volume and Issue: 1003

Published: Jan. 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.

Language: Английский

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A two-experiment approach to hydraulic jump scaling

European Journal of Mechanics - B/Fluids, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Language: Английский

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Renormalized field theory for non-equilibrium systems

Deleted Journal, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 31, 2025

Abstract Renormalized field theory is a most effective framework to carry out asymptotic analysis of non-equilibrium nearly critical systems, especially in high orders perturbation theory. Here, we review some subtle, slippery and non-conventional aspects this approach. We present construction the field-theoretic representation certain Langevin-type stochastic equations with additive multiplicative random sources as well master various birth–death processes. Application renormalization group combined short-distance operator-product expansion scaling behavior reviewed for passive scalar fields advected by velocity ensembles, including Kraichnan’s rapid-change model Navier–Stokes equation. Infinite sets anomalous exponents were calculated within regular expansions up third order. Effects anisotropy, finite correlation time compressibility are discussed. The Kolmogorov constant skewness factor suitable perturbative renormalization-group calculation second-order results presented reasonable agreement experiments fully developed hydrodynamic turbulence. recent third-order directed percolation process presented; paradigmatic models irreversible reaction–diffusion processes discussed account advection fields.

Language: Английский

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Shock tube simulations for the three-layer Richtmyer–Meshkov instability with single-mode and multimode perturbations

Physics of Fluids, Journal Year: 2025, Volume and Issue: 37(2)

Published: Feb. 1, 2025

While the canonical two-component, single-mode Richtmyer–Meshkov instability (RMI) has been extensively studied, relatively less work focused on effects of an additional intermediate-density middle layer. This investigates such three-material RMI configurations at two Atwood number scenarios using ares hydrodynamics code. After validation against previous experimental and computational studies, setups corresponding to recent three-layer shock tube experiments are simulated. Cases with both multimode perturbations studied quantify mixing across interface between materials highest intermediate density. In particular, this is able comprehensibly examine differences two- three-dimensional for problems. Observations from two-layer investigations still apply in setup, but over time horizons considered, there appears be insufficient nonlinear mode coupling create significant simulations following first passage a shock. Additional reshock have growth that does result expected cases do not manifest during horizon studied.

Language: Английский

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Spectrum of Reynolds stress for anisotropic turbulence and Taylor expansion of small-scale velocity

EPJ Web of Conferences, Journal Year: 2025, Volume and Issue: 318, P. 04002 - 04002

Published: Jan. 1, 2025

Solution of the small-scale velocity transport equation for incompressible fluid in anisotropic turbulence as Taylor series time is used obtaining explicit expression Reynolds Stress spectra. The initial condition isotropic with a given turbulent energy spectrum. It assumed that low-order terms are sufficient correct description period about turnover large-scale eddies. averaging taken over this period, integral scale and three uniformly distributed random phases velocity. spectrum given. Craya-Herring components (polarization Fourier components) used. Obtained stress contain mean dissipation rate kinetic energy.

Language: Английский

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Vector resonant relaxation and statistical closure theory: Direct interaction approximation

Physical review. E, Journal Year: 2025, Volume and Issue: 111(4)

Published: April 9, 2025

Language: Английский

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