The role of magnetic boundaries in kinematic and self-consistent magnetohydrodynamic simulations of precession-driven dynamo action in a closed cylinder

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F25%3A00638786" target="_blank" >RIV/67985530:_____/25:00638786 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubs.aip.org/aip/pof/article/37/8/086607/3357716/The-role-of-magnetic-boundaries-in-kinematic-and" target="_blank" >https://pubs.aip.org/aip/pof/article/37/8/086607/3357716/The-role-of-magnetic-boundaries-in-kinematic-and</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1063/5.0274725" target="_blank" >10.1063/5.0274725</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The role of magnetic boundaries in kinematic and self-consistent magnetohydrodynamic simulations of precession-driven dynamo action in a closed cylinder

Popis výsledku v původním jazyce

We numerically examine dynamo action generated by a flow of an electrically conducting fluid in a precessing cylindrical cavity. We compare a kinematic approach with the results from a self-consistent three-dimensional simulation of the complete set of magnetohydrodynamic (MHD) equations. In all cases, we observe a minimum for the onset of dynamo action in a transitional regime, within which the hydrodynamic flow undergoes a change from a large-scale to a more small-scale, turbulent behavior. Significant differences in the critical magnetic Reynolds number occur depending on the physical properties of an external layer surrounding the flow active domain. The strong influence of the electromagnetic properties of this outer layer can be related to two different branches with dynamo action. In contrast to the kinematic models, the nonlinear MHD simulations reveal a small-scale dynamo with the magnetic energy remaining significantly smaller than the kinetic energy. In irregular intervals, we observe dynamo bursts with a local concentration of the magnetic field, resulting in a global increase in the magnetic energy by a factor of 3-5. However, diffusion of the local patches caused by strong local shear is too rapid, causing these features to exist for only a short period so that their dynamical impact on the dynamo remains small. A connection with the kinematic models can be derived by looking at the time-averaged field of the MHD dynamo solution. This is comparable to the eigenmode of the inefficient branch of the kinematic models, which explains their large critical magnetic Reynolds number. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/).

Název v anglickém jazyce

The role of magnetic boundaries in kinematic and self-consistent magnetohydrodynamic simulations of precession-driven dynamo action in a closed cylinder

Popis výsledku anglicky

We numerically examine dynamo action generated by a flow of an electrically conducting fluid in a precessing cylindrical cavity. We compare a kinematic approach with the results from a self-consistent three-dimensional simulation of the complete set of magnetohydrodynamic (MHD) equations. In all cases, we observe a minimum for the onset of dynamo action in a transitional regime, within which the hydrodynamic flow undergoes a change from a large-scale to a more small-scale, turbulent behavior. Significant differences in the critical magnetic Reynolds number occur depending on the physical properties of an external layer surrounding the flow active domain. The strong influence of the electromagnetic properties of this outer layer can be related to two different branches with dynamo action. In contrast to the kinematic models, the nonlinear MHD simulations reveal a small-scale dynamo with the magnetic energy remaining significantly smaller than the kinetic energy. In irregular intervals, we observe dynamo bursts with a local concentration of the magnetic field, resulting in a global increase in the magnetic energy by a factor of 3-5. However, diffusion of the local patches caused by strong local shear is too rapid, causing these features to exist for only a short period so that their dynamical impact on the dynamo remains small. A connection with the kinematic models can be derived by looking at the time-averaged field of the MHD dynamo solution. This is comparable to the eigenmode of the inefficient branch of the kinematic models, which explains their large critical magnetic Reynolds number. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/).

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physics of Fluids

ISSN

1070-6631

e-ISSN

1089-7666

Svazek periodika

37

Číslo periodika v rámci svazku

8

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

13

Strana od-do

086607

Kód UT WoS článku

001561815500001

EID výsledku v databázi Scopus

2-s2.0-105012541604