Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Enhancement of Small-scale Turbulent Dynamo by Large-scale Shear
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
2017 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 850, no 1, article id L8Article in journal (Refereed) Published
Abstract [en]

Small-scale dynamos (SSDs) are ubiquitous in a broad range of turbulent flows with large-scale shear, ranging from solar and galactic magnetism to accretion disks, cosmology, and structure formation. Using high-resolution direct numerical simulations, we show that in non-helically forced turbulence with zero mean magnetic field, large-scale shear supports SSD action, i.e., the dynamo growth rate increases with shear and shear enhances or even produces turbulence, which, in turn, further increases the growth rate. When the production rates of turbulent kinetic energy due to shear and forcing are comparable, we find scalings for the growth rate gamma of the SSD and the turbulent rms velocity u(rms) with shear rate S that are independent of the magnetic Prandtl number: gamma proportional to vertical bar S vertical bar and u(rms) proportional to vertical bar S vertical bar(2/3). For large fluid and magnetic Reynolds numbers, gamma, normalized by its shear-free value, depends only on shear. Having compensated for shear-induced effects on turbulent velocity, we find that the normalized growth rate of the SSD exhibits the scaling, (gamma) over tilde proportional to vertical bar S vertical bar(2/3), arising solely from the induction equation for a given velocity field.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017. Vol. 850, no 1, article id L8
Keywords [en]
dynamo, magnetic fields, magnetohydrodynamics (MHD), turbulence
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-219331DOI: 10.3847/2041-8213/aa96a1ISI: 000415621100004Scopus ID: 2-s2.0-85035326785OAI: oai:DiVA.org:kth-219331DiVA, id: diva2:1162640
Funder
Swedish Research Council, 621-20115076
Note

QC 20171205

Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2017-12-11Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Singh, Nishant K.Rogachevskii, IgorBrandenburg, Axel
By organisation
Nordic Institute for Theoretical Physics NORDITA
In the same journal
Astrophysical Journal Letters
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 9 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf