The fundamental difference between alpha viscosity and turbulent magnetorotational stresses
نویسندگان
چکیده
Numerical simulations of turbulent, magnetized, differentially rotating flows driven by the magnetorotational instability are often used to calculate the effective values of alpha viscosity that is invoked in analytical models of accretion discs. In this paper we use various dynamical models of turbulent magnetohydrodynamic stresses as well as numerical simulations of shearing boxes to show that angular momentum transport in accretion discs cannot be described by the alpha model. In particular, we demonstrate that turbulent magnetorotational stresses are not linearly proportional to the local shear and vanish identically for angular velocity profiles that increase outwards.
منابع مشابه
The fundamental difference between shear alpha-viscosity and turbulent magnetorotational stresses
Numerical simulations of turbulent, magnetized, differentially rotating flows driven by the magnetorotational instability are often used to calculate the effective values of alpha viscosity that is invoked in analytical models of accretion discs. In this paper we use various dynamical models of turbulent magnetohydrodynamic stresses, as well as numerical simulations of shearing boxes, to show t...
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