WFRF:(Singh Nishant K.)
Search: WFRF:(Singh Nishant K.) > (2014) > Large-scale dynamo ...
- 3 of 3
- Previous record
- Next record
- To hitlist
Large-scale dynamo action due to alpha fluctuations in a linear shear flow
- Sridhar, S. (author)
-
- Singh, Nishant K. (author)
- Stockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,Raman Res Inst, Karnataka, India,Nordiska institutet för teoretisk fysik (Nordita),Inter-University Centre for Astronomy & Astrophysics, India
- (creator_code:org_t)
- 2014-10-30
- 2014
- English.
- In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 445:4, s. 3770-3787
- Journal article (peer-reviewed)
Abstract
Subject headings
Close
- We present a model of large-scale dynamo action in a shear flow that has stochastic, zero-mean fluctuations of the a parameter. This is based on a minimal extension of the Kraichnan Moffatt model, to include a background linear shear and Galilean-invariant alpha-statistics. Using the firstorder smoothing approximation we derive a linear integro-differential equation for the largescale magnetic field, which is non-perturbative in the shearing rate S, and the alpha-correlation time r. The white-noise case, tau(alpha) = 0, is solved exactly, and it is concluded that the necessary condition for dynamo action is identical to the Kraichnan Moffatt model without shear; this is because white-noise does not allow for memory effects, whereas shear needs time to act. To explore memory effects we reduce the integro-differential equation to a partial differential equation, valid for slowly varying fields when is small but non-zero. Seeking exponential modal solutions, we solve the modal dispersion relation and obtain an explicit expression for the growth rate as a function of the six independent parameters of the problem. A non-zero r, gives rise to new physical scales, and dynamo action is completely different from the white-noise case; e.g. even weak a fluctuations can give rise to a dynamo. We argue that, at any wavenumber, both Moffatt drift and Shear always contribute to increasing the growth rate. Two examples are presented: (a) a Moffatt drift dynamo in the absence of shear and (b) a Shear dynamo in the absence of Moffatt drift.
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- dynamo
- magnetic fields
- MHD
- turbulence
- galaxies
- magnetic fields
Publication and Content Type
- ref (subject category)
- art (subject category)
Find in a library
- Monthly notices of the Royal Astronomical Society (Search for host publication in LIBRIS)
To the university's database
- 3 of 3
- Previous record
- Next record
- To hitlist
Find more in SwePub
- By the author/editor
- Sridhar, S.
- Singh, Nishant K ...
- About the subject
-
- NATURAL SCIENCES
- NATURAL SCIENCES
- and Physical Science ...
- and Astronomy Astrop ...
- Articles in the publication
- Monthly notices ...
- By the university
- Royal Institute of Technology
- Stockholm University
Search outside SwePub
- Extend your search to:
- Google Book Search
- Google Scholar
Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.
- Copyright © LIBRIS - National Library Systems
- LIBRIS.kb.se
