Related papers: Aspect ratio dependence in magnetorotational insta…
(abridged) Aims: To study turbulent transport coefficients that describe the evolution of large-scale magnetic fields in turbulent convection. Methods: We use the test field method together with 3D numerical simulations of turbulent…
Magnetorotational turbulence and magnetically driven disc winds are often considered as separate processes. However, realistic astrophysical discs are expected to be subject to both effects, although possibly at different times and…
The origin of turbulence in accretion discs is still not fully understood. While the magneto-rotational instability is considered to operate in sufficiently ionized discs, its role in the poorly ionized protoplanetary disc is questionable.…
The shearing instability of a dilute granular mixture composed of smooth inelastic hard spheres or disks is investigated. By using the Navier-Stokes hydrodynamic equations, it is shown that the scaled transversal velocity mode exhibits a…
We study in-plane magnetic tunnel junctions with additional perpendicular polarizer for subnanosecond-current-induced switching memories. The spin-transfer-torque switching dynamics was studied as a function of the cell aspect ratio both…
Shear instabilities can be the source of significant amounts of turbulent mixing in stellar radiative zones. Past attempts at modeling their effects (either theoretically or using numerical simulations) have focused on idealized geometries…
Recent work on the structure of magnetic fields in a turbulent medium gives predictions for the properties of the magnetic flux tubes as a function of the Mach number and scale of the turbulence, and the resistivity and viscosity of the…
A new type of instability that is expected to drive magnetohydrodynamic (MHD) turbulence from a purely toroidal magnetic field in an accretion disk is presented. It is already known that in a differentially rotating system, the uniform…
The magnetorotational instability is thought to play an important role in enabling accretion in sufficiently ionized astrophysical disks. The rate at which MRI-driven turbulence transports angular momentum is related to both the strength of…
The diffusive motion of charged particles in synthetic magnetic turbulence with different properties is investigated by using numerical simulations with unprecedented dynamical range, which allow us to ensure that both the inertial range…
Detailed calculations of the physical structure of accretion disk boundary layers, and thus their inferred observational properties, rely on the assumption that angular momentum transport is opposite to the radial angular frequency gradient…
We study the magneto-rotational instability (MRI) driven dynamo in a geometrically thin disc ($H/R\ll 1$) using stratified zero net flux (ZNF) shearing box simulations. We find that mean fields and EMFs oscillate with a primary frequency…
The effect of magnetic shear on ballooning-driven plasma edge turbulence is studied through nonlinear simulations complemented by linear numerical and analytical investigations. Nonlinear, 3D, global, flux-driven simulations using the GBS…
We examine the role of anisotropic turbulence on the shear instabilities in a stratified flow. Such turbulence is expected to occur in the radiative interiors of stars, due to their differential rotation and their strong stratification, and…
The flow shear associated with the differential toroidal rotation of tokamak plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by the up-down symmetry of the magnetic equilibrium. Using experimental…
Rotationally supported, cold, gaseous disks are ubiquitous in astrophysics and appear in a diverse set of systems, such as protoplanetary disks, accretion disks around black holes, or large spiral galaxies. Capturing the gas dynamics…
The transport of angular momentum (AM) and chemical elements within evolving stars remains poorly understood. Recent observations showed that the radiative cores of low mass main sequence stars and red giants rotate orders of magnitude…
First results from a high-resolution three-dimensional nonlinear numerical study of the kink oscillation are presented. We show in detail the development of a shear instability in an untwisted line-tied magnetic flux tube. The instability…
The status of our current understanding of angular momentum transport in accretion disks is reviewed. The last decade has seen a dramatic increase both in the recognition of key physical processes and in our ability to carry through direct…
We determine how MRI-turbulent stresses depend on gas pressure via a suite of unstratified shearing box simulations. Earlier numerical work reported only a very weak dependence at best, results that call into question the canonical…