Available Energy and Ground States of Convective Hydrodynamic and Hydromagnetic Instabilities

Fuente: arXiv
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Autori principali: Fan, Kaixuan, Zhou, Yao
Natura: Preprint
Pubblicazione: 2026
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author Fan, Kaixuan
Zhou, Yao
author_facet Fan, Kaixuan
Zhou, Yao
contents We propose a method for predicting the nonlinear saturation level of convective instabilities in neutral and magnetized fluids. The method combines Gardner's restacking algorithm, which computes the available energy and ground states of collisionless plasmas in phase space, and Lagrangian relaxation, where fluid elements find lower-energy equilibria while preserving local invariants. For the incompressible Rayleigh-Taylor instability, the problem is formally equivalent to Gardner's and the restacking algorithm directly applies in configuration space. To treat compressibility, we follow restacking with Lagrangian relaxation to obtain the ground state, and the results show excellent agreement with direct numerical simulations. Successful extension to the $m=0$ interchange instability in a Z-pinch demonstrates the method's potential as a general framework for estimating the nonlinear extent of convective instabilities, which can facilitate the design and operation of fusion reactors.
format Preprint
id arxiv_https___arxiv_org_abs_2602_23983
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Available Energy and Ground States of Convective Hydrodynamic and Hydromagnetic Instabilities
Fan, Kaixuan
Zhou, Yao
Plasma Physics
We propose a method for predicting the nonlinear saturation level of convective instabilities in neutral and magnetized fluids. The method combines Gardner's restacking algorithm, which computes the available energy and ground states of collisionless plasmas in phase space, and Lagrangian relaxation, where fluid elements find lower-energy equilibria while preserving local invariants. For the incompressible Rayleigh-Taylor instability, the problem is formally equivalent to Gardner's and the restacking algorithm directly applies in configuration space. To treat compressibility, we follow restacking with Lagrangian relaxation to obtain the ground state, and the results show excellent agreement with direct numerical simulations. Successful extension to the $m=0$ interchange instability in a Z-pinch demonstrates the method's potential as a general framework for estimating the nonlinear extent of convective instabilities, which can facilitate the design and operation of fusion reactors.
title Available Energy and Ground States of Convective Hydrodynamic and Hydromagnetic Instabilities
topic Plasma Physics
url https://arxiv.org/abs/2602.23983