Nonlinear transverse cascade and sustenance of MRI-turbulence in Keplerian disks with an azimuthal magnetic field
arXiv:1707.07044 · doi:10.3847/1538-4357/aa7ed1
Abstract
We investigate magnetohydrodynamic turbulence driven by the magnetorotational instability (MRI) in Keplerian disks with a nonzero net azimuthal magnetic field using shearing box simulations. As distinct from most previous studies, we analyze turbulence dynamics in Fourier (-) space to understand its sustenance. The linear growth of MRI with azimuthal field has a transient character and is anisotropic in Fourier space, leading to anisotropy of nonlinear processes in Fourier space. As a result, the main nonlinear process appears to be a new type of angular redistribution of modes in Fourier space -- the \emph{nonlinear transverse cascade} -- rather than usual direct/inverse cascade. We demonstrate that the turbulence is sustained by interplay of the linear transient growth of MRI (which is the only energy supply for the turbulence) and the transverse cascade. These two processes operate at large length scales, comparable to box size and the corresponding small wavenumber area, called \emph{vital area} in Fourier space is crucial for the sustenance, while outside the vital area direct cascade dominates. The interplay of the linear and nonlinear processes in Fourier space is generally too intertwined for a vivid schematization. Nevertheless, we reveal the \emph{basic subcycle} of the sustenance that clearly shows synergy of these processes in the self-organization of the magnetized flow system. This synergy is quite robust and persists for the considered different aspect ratios of the simulation boxes. The spectral characteristics of the dynamical processes in these boxes are qualitatively similar, indicating the universality of the sustenance mechanism of the MRI-turbulence.
arXiv comment32 pages, 17 figures, accepted for publication in ApJ
References in corpus (61)
- Dynamics of Protoplanetary Disks
- Enhanced Angular Momentum Transport in Accretion Disks
- Zonal Flows and Long-Lived Axisymmetric Pressure Bumps in Magnetorotational Turbulence
- Sustained Magnetorotational Turbulence in Local Simulations of Stratified Disks with Zero Net Magnetic Flux
- Statistical Theory of Magnetohydrodynamic Turbulence: Recent Results
- MHD simulations of the magnetorotational instability in a shearing box with zero net flux. II. The effect of transport coefficients
- Impact of dimensionless numbers on the efficiency of MRI-induced turbulent transport
- The Effect of Resistivity on the Nonlinear Stage of the Magnetorotational Instability in Accretion Disks
- MHD simulations of the magnetorotational instability in a shearing box with zero net flux. I. The issue of convergence
- Angular Momentum Transport in Accretion Disks: Scaling Laws in MRI-driven Turbulence
- Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
- Turbulence and Steady Flows in 3D Global Stratified MHD Simulations of Accretion Disks
- Global Simulations of Accretion Disks I: Convergence and Comparisons with Local Models
- Magnetic Flux Concentration and Zonal Flows in Magnetorotational Instability Turbulence
- Testing Convergence for Global Accretion Disks
- The Nuclear Stellar Disk in Andromeda: A Fossil from the Era of Black Hole Growth
- Locality of MHD Turbulence in Isothermal Disks
- On Self-Sustained Dynamo Cycles in Accretion Discs
- On hydrodynamic shear turbulence in Keplerian disks: via transient growth to bypass transition
- Aspect ratio dependence in magnetorotational instability shearing box simulations
- Convection Causes Enhanced Magnetic Turbulence in Accretion Disks in Outburst
- Simulations of Magnetorotational Turbulence with a Higher-Order Godunov Scheme
- Saturation of the magnetorotational instability in the unstratified shearing box with zero net flux: convergence in taller boxes
- MRI channel flows and their parasites
- Turbulence in weakly-ionized proto-planetary disks
- On the Saturation of the Magnetorotational Instability via Parasitic Modes
- Bypass to Turbulence in Hydrodynamic Accretion Disks: An Eigenvalue Approach
- Turbulence in Global Simulations of Magnetized Thin Accretion Disks
- Viscous and Resistive Effects on the MRI with a Net Toroidal Field
- MRI-driven turbulent transport: the role of dissipation, channel modes and their parasites
- Angular Momentum Transport in Protoplanetary and Black-Hole Accretion Disks: The Role of Parasitic Modes in the Saturation of MHD Turbulence
- Radially Extended, Stratified, Local Models of Isothermal Disks
- On the angular momentum transport due to vertical convection in accretion discs
- Periodic magnetorotational dynamo action as a prototype of nonlinear magnetic field generation in shear flows
- Dynamic anisotropy in MHD turbulence induced by mean magnetic field
- Large Scale Azimuthal Structures Of Turbulence In Accretion Disks - Dynamo triggered variability of accretion
- Nonlinear energy transfers in accretion discs MRI turbulence. I-Net vertical field case
- MHD simulations of the magnetorotational instability in a shearing box with zero net flux: the case Pm=4
- Angular momentum transport and large eddy simulations in magnetorotational turbulence: the small Pm limit
- On the Nature of Magnetic Turbulence in Rotating, Shearing Flows
- Symmetries, scaling laws and convergence in shearing-box simulations of MRI driven turbulence
- Revisiting linear dynamics of non-axisymmetric perturbations in weakly magnetized accretion discs
- On the convergence of Magnetorotational turbulence in stratified isothermal shearing boxes
- Global simulations of magnetorotational turbulence I: convergence and the quasi-steady state
- Dissipative effects on the sustainment of a magnetorotational dynamo in Keplerian shear flow
- Dynamics of homogeneous shear turbulence: A key role of the nonlinear transverse cascade in the bypass concept
- Magnetorotational dynamo chimeras. The missing link to turbulent accretion disk dynamo models?
- Nonlinear transverse cascade and two-dimensional magnetohydrodynamic subcritical turbulence in plane shear flows
- Magnetorotational turbulence in stratified shearing boxes with perfect gas equation of state and finite thermal diffusivity
- Magnetorotational instability: nonmodal growth and the relationship of global modes to the shearing box
- On Hydromagnetic Stresses in Accretion Disk Boundary Layers
- On the Anisotropic Nature of MRI-Driven Turbulence in Astrophysical Disks
- Nonaxisymmetric stability in the shearing sheet approximation
- Magnetohydrodynamic Shearing Waves
- A study of transient dynamics of perturbations in Keplerian discs using a variational approach
- On characterizing nonlocality and anisotropy for the magnetorotational instability
- The stress-pressure relationship in simulations of MRI-induced turbulence
- Fully Convective Magnetorotational Turbulence in Stratified Shearing Boxes
- Universal small-scale structure in turbulence driven by magnetorotational instability
- Transient growth of perturbations on scales beyond the accretion disc thickness
- Regimes of the non-exponential temporal growth in thin Keplerian discs under toroidally-dominated magnetic fields
Cited by in corpus (9)
- MRI turbulence in accretion discs at large magnetic Prandtl numbers
- Zero net flux MRI-turbulence in disks sustenance scheme and magnetic Prandtl number dependence
- Simulating the magnetorotational instability on a moving mesh with the shearing box approximation
- Active modes and dynamical balances in MRI-turbulence of Keplerian disks with a net vertical magnetic field
- MRI turbulence in vertically stratified accretion discs at large magnetic Prandtl numbers
- Hydrodynamical instability with noise in the Keplerian accretion discs: Modified Landau equation
- Impact of magnetic field gradients on the development of the MRI: Applications to binary neutron star mergers and proto-planetary disks
- Subcritical transition to turbulence in accretion disc boundary layer
- Turbulence and order in magnetized flowing plasmas