Impact of dimensionless numbers on the efficiency of MRI-induced turbulent transport

Abstract

The magneto-rotational instability is presently the most promising source of turbulent transport in accretion disks. However, some important issues still need to be addressed to quantify the role of MRI in disks; in particular no systematic investigation of the role of the physical dimensionless parameters of the problem on the dimensionless transport has been undertaken yet. First, we complete existing investigations on the field strength dependence by showing that the transport in high magnetic pressure disks close to marginal stability is highly time-dependent and surprisingly efficient. Second, we bring to light a significant dependence of the global transport on the magnetic Prandtl number, with $\alpha \propto P{m}^{\delta }$ for the explored range: $0.12<Pm<8$ and $200<Re<6400$ ($\delta$ being in the range 0.25 to 0.5). We show that the dimensionless transport is not correlated to the dimensionless linear growth rate, contrarily to a largely held expectation. More generally, these results stress the need to control dissipation processes in astrophysical simulations.

11 pages, 11 figures, accepted to MNRAS

Cited by in corpus (15)

• Global MHD simulations of stratified and turbulent protoplanetary discs. II. Dust settling
• On Self-Sustained Dynamo Cycles in Accretion Discs
• New composite models of partially ionized protoplanetary disks
• Aspect ratio dependence in magnetorotational instability shearing box simulations
• Simulations of Magnetorotational Turbulence with a Higher-Order Godunov Scheme
• High accretion rates in magnetised Keplerian discs mediated by a Parker instability driven dynamo
• Numerical experiments on dynamo action in sheared and rotating turbulence
• Axisymmetric Magnetorotational Instability in Viscous Accretion Disks
• Subcritical dynamos in shear flows
• Localized magnetorotational instability and its role in the accretion disc dynamo
• Microphysical dissipation, turbulence and magnetic fields in hyper-accreting discs
• Magnetic Fields In Astrophysical Objects
• Interaction of the magnetorotational instability with hydrodynamic turbulence in accretion disks
• Spectral Methods for Time-Dependent Studies of Accretion Flows. III. Three-Dimensional, Self-gravitating, Magnetohydrodynamic Disks
• Hydrodynamical activity in thin accretion disks