%0 Journal Article
%T On the nature of magnetic turbulence in rotating, shearing flows
%+ Institut de Planétologie et d'Astrophysique de Grenoble (IPAG)
%A Walker, Justin
%A Lesur, Geoffroy
%A Boldyrev, Stanislav
%< avec comité de lecture
%@ 1745-3933
%J Monthly Notices of the Royal Astronomical Society: Letters
%I Oxford Journals
%V 457
%P L39-L43
%8 2016
%D 2016
%Z 1512.03739
%Z 2016MNRAS.457L..39W
%R 10.1093/mnrasl/slv200
%K accretion
%K accretion discs
%K dynamo
%K MHD
%K plasmas
%K Astrophysics - Solar and Stellar Astrophysics
%K Astrophysics - High Energy Astrophysical Phenomena
%K Physics - Fluid Dynamics
%K Physics - Plasma Physics
%Z Sciences of the Universe [physics]
%Z Sciences of the Universe [physics]/Astrophysics [astro-ph]Journal articles
%X The local properties of turbulence driven by the magnetorotational instability (MRI) in rotating, shearing flows are studied in the framework of a shearing-box model. Based on numerical simulations, we propose that the MRI-driven turbulence comprises two components: the large-scale shear-aligned strong magnetic field and the small-scale fluctuations resembling magnetohydrodynamic (MHD) turbulence. The energy spectrum of the large-scale component is close to k-2, whereas the spectrum of the small-scale component agrees with the spectrum of strong MHD turbulence k-3/2. While the spectrum of the fluctuations is universal, the outer-scale characteristics of the turbulence are not; they depend on the parameters of the system, such as the net magnetic flux. However, there is remarkable universality among the allowed turbulent states - their intensity v0 and their outer scale λ0 satisfy the balance condition v0/λ0 ∼ dΩ/dln r, where dΩ/dln r is the local orbital shearing rate of the flow. Finally, we find no sustained dynamo action in the Pm = 1 zero net-flux case for Reynolds numbers as high as 45 000, casting doubts on the existence of an MRI dynamo in the Pm ≤ 1 regime.
%G English
%2 https://insu.hal.science/insu-03691562/document
%2 https://insu.hal.science/insu-03691562/file/slv200.pdf
%L insu-03691562
%U https://insu.hal.science/insu-03691562
%~ INSU
%~ UNIV-SAVOIE
%~ UGA
%~ CNRS
%~ INPG
%~ IRSTEA
%~ CNES
%~ OSUG
%~ IPAG
%~ AGREENIUM
%~ INRAE
%~ UGA-COMUE
%~ USMB-COMUE
%~ TEST3-HALCNRS