Spectral Transfers of Sign-Definite Invariants in Wave Turbulence

Fuente: arXiv
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Hauptverfasser: Salvatore, Nicholas R., Dematteis, Giovanni, Lvov, Yuri V.
Format: Preprint
Veröffentlicht: 2025
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author Salvatore, Nicholas R.
Dematteis, Giovanni
Lvov, Yuri V.
author_facet Salvatore, Nicholas R.
Dematteis, Giovanni
Lvov, Yuri V.
contents We consider the spectral transfers of sign-definite invariants in general wave turbulence systems equipped with a wave kinetic equation. We develop a formalism to investigate and to characterize these transfers, based on the ability to track the exchanges within individual interactions by the detailed-conservation properties of the resonant interactions. We consider the three-wave, four-wave, five-wave and six-wave kinetic equations, introducing measures of locality of general wave turbulence system and of median step size in wave-wave scattering. We then use the proposed method to study the Majda-McLaughlin-Tabak one-dimensional model and examine the characteristics of energy and action transport. We show that energy in the direct energy cascade is dominated by local interactions, but shows a nonlocal inverse "return flow" that counters the direction of the cascade. The inverse action cascade is instead ruled by more nonlocal interactions, but shows a highly local direct "return flow". We also show that for both cascades a scale separation of over an order of magnitude is necessary to ensure a negligible interaction rate with forcing or dissipation regions, hinting at why in numerical simulations of the model an extremely large box size is necessary in order to realize the theoretical Kolmogorov-Zakharov spectra.
format Preprint
id arxiv_https___arxiv_org_abs_2503_15533
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spectral Transfers of Sign-Definite Invariants in Wave Turbulence
Salvatore, Nicholas R.
Dematteis, Giovanni
Lvov, Yuri V.
Chaotic Dynamics
Fluid Dynamics
We consider the spectral transfers of sign-definite invariants in general wave turbulence systems equipped with a wave kinetic equation. We develop a formalism to investigate and to characterize these transfers, based on the ability to track the exchanges within individual interactions by the detailed-conservation properties of the resonant interactions. We consider the three-wave, four-wave, five-wave and six-wave kinetic equations, introducing measures of locality of general wave turbulence system and of median step size in wave-wave scattering. We then use the proposed method to study the Majda-McLaughlin-Tabak one-dimensional model and examine the characteristics of energy and action transport. We show that energy in the direct energy cascade is dominated by local interactions, but shows a nonlocal inverse "return flow" that counters the direction of the cascade. The inverse action cascade is instead ruled by more nonlocal interactions, but shows a highly local direct "return flow". We also show that for both cascades a scale separation of over an order of magnitude is necessary to ensure a negligible interaction rate with forcing or dissipation regions, hinting at why in numerical simulations of the model an extremely large box size is necessary in order to realize the theoretical Kolmogorov-Zakharov spectra.
title Spectral Transfers of Sign-Definite Invariants in Wave Turbulence
topic Chaotic Dynamics
Fluid Dynamics
url https://arxiv.org/abs/2503.15533