Quenching and anisotropy of hydromagnetic turbulent transport

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Karak, Bidya Binay
dc.contributor.author Rheinhardt, Matthias
dc.contributor.author Brandenburg, Axel
dc.contributor.author Käpylä, Petri J.
dc.contributor.author Käpylä, Maarit J.
dc.date.accessioned 2018-08-01T13:28:43Z
dc.date.available 2018-08-01T13:28:43Z
dc.date.issued 2014
dc.identifier.citation Karak , B B , Rheinhardt , M , Brandenburg , A , Käpylä , P J & Käpylä , M J 2014 , ' Quenching and anisotropy of hydromagnetic turbulent transport ' ASTROPHYSICAL JOURNAL , vol 795 , no. 1 . DOI: 10.1088/0004-637X/795/1/16 en
dc.identifier.issn 0004-637X
dc.identifier.issn 1538-4357
dc.identifier.other PURE UUID: 6b4a1664-fc67-4162-8f07-aae34cb77bd6
dc.identifier.other PURE ITEMURL: https://research.aalto.fi/en/publications/quenching-and-anisotropy-of-hydromagnetic-turbulent-transport(6b4a1664-fc67-4162-8f07-aae34cb77bd6).html
dc.identifier.other PURE LINK: http://iopscience.iop.org/0004-637X/795/1/16/
dc.identifier.other PURE FILEURL: https://research.aalto.fi/files/26502912/Karak_2014_ApJ_795_16.pdf
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/32799
dc.description VK: resolve; Karhunen, J.; ReSoLVE
dc.description.abstract Hydromagnetic turbulence affects the evolution of large-scale magnetic fields through mean-field effects like turbulent diffusion and the α effect. For stronger fields, these effects are usually suppressed or quenched, and additional anisotropies are introduced. Using different variants of the test-field method, we determine the quenching of the turbulent transport coefficients for the forced Roberts flow, isotropically forced non-helical turbulence, and rotating thermal convection. We see significant quenching only when the mean magnetic field is larger than the equipartition value of the turbulence. Expressing the magnetic field in terms of the equipartition value of the quenched flows, we obtain for the quenching exponents of the turbulent magnetic diffusivity about 1.3, 1.1, and 1.3 for Roberts flow, forced turbulence, and convection, respectively. However, when the magnetic field is expressed in terms of the equipartition value of the unquenched flows, these quenching exponents become about 4, 1.5, and 2.3, respectively. For the α effect, the exponent is about 1.3 for the Roberts flow and 2 for convection in the first case, but 4 and 3, respectively, in the second. In convection, the quenching of turbulent pumping follows the same power law as turbulent diffusion, while for the coefficient describing the Omega x J effect nearly the same quenching exponent is obtained as for α. For forced turbulence, turbulent diffusion proportional to the second derivative along the mean magnetic field is quenched much less, especially for larger values of the magnetic Reynolds number. However, we find that in corresponding axisymmetric mean-field dynamos with dominant toroidal field the quenched diffusion coefficients are the same for the poloidal and toroidal field constituents. en
dc.format.extent 16
dc.format.mimetype application/pdf
dc.language.iso en en
dc.relation.ispartofseries ASTROPHYSICAL JOURNAL en
dc.relation.ispartofseries Volume 795, issue 1 en
dc.rights openAccess en
dc.title Quenching and anisotropy of hydromagnetic turbulent transport en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department Centre of Excellence Research on Solar Long-Term Variability and Effects, ReSoLVE
dc.identifier.urn URN:NBN:fi:aalto-201808014200
dc.identifier.doi 10.1088/0004-637X/795/1/16
dc.type.version publishedVersion

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