CONNECTIONS BETWEEN LOCAL AND GLOBAL TURBULENCE IN ACCRETION DISKS
- Department of Mathematics and Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
- Joint Space Science Institute (JSI), University of Maryland, College Park, MD 20742-2421 (United States)
- JILA, 440 UCB, University of Colorado, Boulder, CO 80309-0440 (United States)
We analyze a suite of global magnetohydrodynamic (MHD) accretion disk simulations in order to determine whether scaling laws for turbulence driven by the magnetorotational instability, discovered via local shearing-box studies, are globally robust. The simulations model geometrically thin disks with zero net magnetic flux and no explicit resistivity or viscosity. We show that the local Maxwell stress is correlated with the self-generated local vertical magnetic field in a manner that is similar to that found in local simulations. Moreover, local patches of vertical field are strong enough to stimulate and control the strength of angular momentum transport across much of the disk. We demonstrate the importance of magnetic linkages (through the low-density corona) between different regions of the disk in determining the local field, and suggest a new convergence requirement for global simulations-the vertical extent of the corona must be fully captured and resolved. Finally, we examine the temporal convergence of the average stress and show that an initial long-term secular drift in the local flux-stress relation dies away on a timescale that is consistent with turbulent mixing of the initial magnetic field.
- OSTI ID:
- 21394204
- Journal Information:
- Astrophysical Journal, Vol. 712, Issue 2; Other Information: DOI: 10.1088/0004-637X/712/2/1241; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
EQUILIBRIUM DISKS, MAGNETOROTATIONAL INSTABILITY MODE EXCITATION, AND STEADY-STATE TURBULENCE IN GLOBAL ACCRETION DISK SIMULATIONS
Magnetohydrodynamic simulations of global accretion disks with vertical magnetic fields