VISCOUS AND RESISTIVE EFFECTS ON THE MAGNETOROTATIONAL INSTABILITY WITH A NET TOROIDAL FIELD

摘要: Resistivity and viscosity have a significant role in establishing the energy levels turbulence driven by magnetorotational instability (MRI) local astrophysical disk models. This study uses Athena code to characterize effects of constant shear \nu Ohmic resistivity \eta unstratified shearing box simulations with net toroidal magnetic flux. A previous boxes zero field performed ZEUS found that dies out for values Prandtl number, P_m = \nu/\eta, below \sim 1; \gtrsim 1, time- volume-averaged stress increase P_m. We repeat these experiments obtain consistent results. Next, influence on MRI is investigated both linear growth fully-developed turbulence. In regime, sufficiently large or can prevent growth; itself has little direct from perturbations. By applying range an initial state consisting fully developed presence background field, we investigate their nonlinear system. Here, increased enhances turbulence, decays only if above critical value; be sustained even when < contrast model. While find preliminary evidence converges small become enough, dissipation terms MRI-driven relatively significant, independent geometry.