2001/01/26 by R. Arlt, G. Rudiger, G. Rüdiger · 2 citations
Physics and Astronomy · #Accretion (finance) #Angular momentum #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Dynamo #Dynamo theory #Instability #Magnetic Reynolds number #Magnetic diffusivity #Magnetic field #Magnetohydrodynamics #Mechanics #Physics #Reynolds number #Stellar, planetary, and galactic studies #Turbulence #astro-ph
paper · pdf · doi:10.1051/0004-6361:20010797
13 pages, LaTeX, submitted to A&A
arxiv created 2001/01/26 · openalex publication_date 2001/08/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We perform global three-dimensional simulations of accretion disks integrating the compressible, non-viscous, but diffusive MHD equations. The disk is supposed to be isothermal. We make use of the ZEUS-3D code integrating the MHD equations and added magnetic diffusivity. We measure the efficiency of the angular-momentum transport. Various model simulations delivered transport parameters of to 0.05 which are consistent with several local numerical investigations. Two of the models reach a highly turbulent state at which is of the order of 0.1. After a certain stage of saturating of the turbulence, Reynolds stress is found to be negative (inward transport) in many of the models, whereas Maxwell stresses dominate and deliver a positive (outward) total transport. Several of the models yield strongly fluctuating Reynolds stresses, while Maxwell stresses are smooth and always transport outwards. Dynamo action is found in the accretion disk simulations. A positive dynamo-α is indicated in the northern hemisphere of the most prominent run, coming along with negative kinetic and current helicities (all having the opposite sign on the southern side). The dipolar structure of the magnetic field is maintained throughout the simulations, although indication for a decay of antisymmetry is found. The simulations covered relatively thick disks, and results of thin-disk dynamo models showing quadrupolar fields may not be compatible with the results presented here.