Change search
ReferencesLink to record
Permanent link

Direct link
Dissipation in dynamos at low and high magnetic Prandtl numbers
Stockholm University, Nordic Institute for Theoretical Physics (Nordita).
2011 (English)In: Astronomical Notes - Astronomische Nachrichten, ISSN 0004-6337, E-ISSN 1521-3994, Vol. 332, no 1, 51-56 p.Article in journal (Refereed) Published
Abstract [en]

Using simulations of helically driven turbulence, it is shown that the ratio of kinetic to magnetic energy dissipation scales with the magnetic Prandtl number in power law fashion with an exponent of approximately 0.6. Over six orders of magnitude in the magnetic Prandtl number the magnetic field is found to be sustained by large-scale dynamo action of alpha-squared type. This work extends a similar finding for small magnetic Prandtl numbers to the regime of large magnetic Prandtl numbers. At large magnetic Prandtl numbers, most of the energy is dissipated viscously, lowering thus the amount of magnetic energy dissipation, which means that simulations can be performed at magnetic Reynolds numbers that are large compared to the usual limits imposed by a given resolution. This is analogous to an earlier finding that at small magnetic Prandtl numbers, most of the energy is dissipated resistively, lowering the amount of kinetic energy dissipation, so simulations can then be performed at much larger fluid Reynolds numbers than otherwise. The decrease in magnetic energy dissipation at large magnetic Prandtl numbers is discussed in the context of underluminous accretion found in some quasars.

Place, publisher, year, edition, pages
2011. Vol. 332, no 1, 51-56 p.
Keyword [en]
magnetic fields, magnetohydrodynamics (MHD)
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-68369DOI: 10.1002/asna.201011478ISI: 000286855400008OAI: diva2:472866
authorCount :1Available from: 2012-01-04 Created: 2012-01-03 Last updated: 2012-01-04Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Brandenburg, Axel
By organisation
Nordic Institute for Theoretical Physics (Nordita)
In the same journal
Astronomical Notes - Astronomische Nachrichten
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 18 hits
ReferencesLink to record
Permanent link

Direct link