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Global three dimensional magnetohydrodynamic (MHD) simulations of turbulentaccretion disks are presented which start from fully equilibrium initialconditions in which the magnetic forces are accounted for and the inductionequation is satisfied. The local linear theory of the magnetorotationalinstability (MRI) is used as a predictor of the growth of magnetic fieldperturbations in the global simulations. The linear growth estimates and globalsimulations diverge when non-linear motions - perhaps triggered by the onset ofturbulence - upset the velocity perturbations used to excite the MRI. Thesaturated state is found to be independent of the initially excited MRI mode,showing that once the disk has expelled the initially net flux field andsettled into quasi-periodic oscillations in the toroidal magnetic flux, thedynamo cycle regulates the global saturation stress level. Furthermore,time-averaged measures of converged turbulence, such as the ratio of magneticenergies, are found to be in agreement with previous works. In particular, theglobally averaged stress normalized to the gas pressure, <\alpha_{\rm P}> =0.034, with notably higher values achieved for simulations with higherazimuthal resolution. Supplementary tests are performed using differentnumerical algorithms and resolutions. Convergence with resolution during theinitial linear MRI growth phase is found for 23-35 cells per scaleheight (inthe vertical direction).

Equilibrium disks, MRI mode excitation, and steady state turbulence in global accretion disk simulations