Wave-like Spiral Interactions and the Emergence of Quasi-Biennial Oscillations in Strato-Rotational Flows

Fuente: arXiv
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Hauptverfasser: Meletti, Gabriel, Abide, Stéphane, Viazzo, Stéphane, Curbelo, Jezabel, Harlander, Uwe
Format: Preprint
Veröffentlicht: 2025
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author Meletti, Gabriel
Abide, Stéphane
Viazzo, Stéphane
Curbelo, Jezabel
Harlander, Uwe
author_facet Meletti, Gabriel
Abide, Stéphane
Viazzo, Stéphane
Curbelo, Jezabel
Harlander, Uwe
contents This study investigates the dynamics of Strato-Rotational Instability (SRI) in a stratified, rotating fluid, focusing on the interaction between axial modes and spiral components. Through numerical analysis, we find that SRI induces oscillatory behaviors that change the mean flow, leading to the selective activation of distinct axial wavenumbers associated with upward and downward propagating spiral modes. These results suggest wave-mean flow interactions. The use of Radon Transforms (RT) allowed us to separate these spiral components, showing that each upward and downward component was individually modulated, but out of phase with each other. Inspired by the RT findings, a simplified toy model was developed to interpret the spiral pattern changes linked to amplitude modulations. The model considers two wave-like spirals propagating in opposite axial directions, linearly interacting. By incorporating out-of-phase individual spiral modulations, the model reproduces the observed spiral pattern transitions, offering a straightforward interpretation of the underlying physical processes. To explore the mechanism of individual spiral modulations, we consider a Quasi-Biennial Oscillation (QBO)-like framework derived from the Navier-Stokes equations in a rotating frame. These findings contribute to a better understanding of low-frequency SRI dynamics and may offer insights into similar phenomena in geophysical and astrophysical contexts.
format Preprint
id arxiv_https___arxiv_org_abs_2509_06691
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Wave-like Spiral Interactions and the Emergence of Quasi-Biennial Oscillations in Strato-Rotational Flows
Meletti, Gabriel
Abide, Stéphane
Viazzo, Stéphane
Curbelo, Jezabel
Harlander, Uwe
Fluid Dynamics
76D50, 76E07, 76E09, 76E20, 76B60, 76E30, 76M20, 76M22, 76M25
This study investigates the dynamics of Strato-Rotational Instability (SRI) in a stratified, rotating fluid, focusing on the interaction between axial modes and spiral components. Through numerical analysis, we find that SRI induces oscillatory behaviors that change the mean flow, leading to the selective activation of distinct axial wavenumbers associated with upward and downward propagating spiral modes. These results suggest wave-mean flow interactions. The use of Radon Transforms (RT) allowed us to separate these spiral components, showing that each upward and downward component was individually modulated, but out of phase with each other. Inspired by the RT findings, a simplified toy model was developed to interpret the spiral pattern changes linked to amplitude modulations. The model considers two wave-like spirals propagating in opposite axial directions, linearly interacting. By incorporating out-of-phase individual spiral modulations, the model reproduces the observed spiral pattern transitions, offering a straightforward interpretation of the underlying physical processes. To explore the mechanism of individual spiral modulations, we consider a Quasi-Biennial Oscillation (QBO)-like framework derived from the Navier-Stokes equations in a rotating frame. These findings contribute to a better understanding of low-frequency SRI dynamics and may offer insights into similar phenomena in geophysical and astrophysical contexts.
title Wave-like Spiral Interactions and the Emergence of Quasi-Biennial Oscillations in Strato-Rotational Flows
topic Fluid Dynamics
76D50, 76E07, 76E09, 76E20, 76B60, 76E30, 76M20, 76M22, 76M25
url https://arxiv.org/abs/2509.06691