Turbulent dynamo in the shell model and the Kazantsev-Kraichnan approach

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F25%3A10502855" target="_blank" >RIV/00216208:11320/25:10502855 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=FgmHdw3GKN" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=FgmHdw3GKN</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/vf15-z9hf" target="_blank" >10.1103/vf15-z9hf</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Turbulent dynamo in the shell model and the Kazantsev-Kraichnan approach

Popis výsledku v původním jazyce

We investigate small-scale magnetic energy generation in a turbulent conducting flow using two different approaches. One is based on the Kazantsev-Kraichnan (KK) model, developed for a random velocity field with short time correlations, and the other uses the shell magnetohydrodynamic (MHD) method, which describes a turbulent energy cascade on a finite number of spectral shells. We consider only the kinematic (linear) regime and show an exponential growth of magnetic energy for sufficiently large magnetic Reynolds numbers (Rm) in both approaches. By comparing the dependencies of the growth rates at different Rm, we try to answer the question how the model assumptions-of short time correlations or of finite spectral shells-affect the turbulent dynamo possibility and the position of the Rm threshold at which this generation starts. We analyze the generation behavior at different Reynolds and magnetic Prandtl numbers, which are not explicitly included in the KK model but taken into account in the shell approach. Based on the obtained results, we try to discuss why the small-scale generation has not been observed in real MHD dynamo experiments so far.

Název v anglickém jazyce

Turbulent dynamo in the shell model and the Kazantsev-Kraichnan approach

Popis výsledku anglicky

We investigate small-scale magnetic energy generation in a turbulent conducting flow using two different approaches. One is based on the Kazantsev-Kraichnan (KK) model, developed for a random velocity field with short time correlations, and the other uses the shell magnetohydrodynamic (MHD) method, which describes a turbulent energy cascade on a finite number of spectral shells. We consider only the kinematic (linear) regime and show an exponential growth of magnetic energy for sufficiently large magnetic Reynolds numbers (Rm) in both approaches. By comparing the dependencies of the growth rates at different Rm, we try to answer the question how the model assumptions-of short time correlations or of finite spectral shells-affect the turbulent dynamo possibility and the position of the Rm threshold at which this generation starts. We analyze the generation behavior at different Reynolds and magnetic Prandtl numbers, which are not explicitly included in the KK model but taken into account in the shell approach. Based on the obtained results, we try to discuss why the small-scale generation has not been observed in real MHD dynamo experiments so far.

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

<a href="/cs/project/LUAUS25060" target="_blank" >LUAUS25060: Jak a kde je sluneční vítr urychlován a zahříván a jak tyto procesy ovlivňují jeho šíření heliosférou?</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2025

Kód důvěrnosti údajů

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

Název periodika

Physical Review E

ISSN

2470-0045

e-ISSN

2470-0053

Svazek periodika

112

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

10

Strana od-do

015104

Kód UT WoS článku

001537519700003

EID výsledku v databázi Scopus

2-s2.0-105013825015