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Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in…

Astrophysics · Physics 2009-11-11 P. D. Mininni

Simulations of astrophysical disks in the shearing box that are subject to the magnetorotational instability (MRI) show that activity appears to be reduced as the magnetic Prandtl number (Pm) is lowered. On the other hand, calculations for…

Solar and Stellar Astrophysics · Physics 2015-05-18 O. M. Umurhan

We study the magneto-rotational instability of an incompressible flow which rotates with angular velocity Omega(r)=a+b/r^2 where r is the radius and $a$ and b are constants. We find that an applied magnetic field destabilises the flow, in…

Astrophysics · Physics 2008-11-26 Ashley P. Willis , Carlo F. Barenghi

Using the test-field method for nearly irrotational turbulence driven by spherical expansion waves it is shown that the turbulent magnetic diffusivity increases with magnetic Reynolds numbers. Its value levels off at several times the rms…

Astrophysics of Galaxies · Physics 2010-11-05 Axel Brandenburg , Fabio Del Sordo

The aim of this Letter is to characterize the flow regimes of suspensions of finite-size rigid particles in a viscous fluid at finite inertia. We explore the system behavior as function of the particle volume fraction and the Reynolds…

Fluid Dynamics · Physics 2015-06-18 Iman Lashgari , Francesco Picano , Wim-Paul Breugem , Luca Brandt

To study the Reynolds stresses which describe turbulent momentum transport from turbulence affected by large-scale shear and rotation. Three-dimensional numerical simulations are used to study turbulent transport under the influences of…

Solar and Stellar Astrophysics · Physics 2009-11-19 J. E. Snellman , P. J. Käpylä , M. J. Korpi , A. J. Liljeström

A large eddy simulation (LES) with an extended Smagorinsky model has been carried to investigate numerically the fully developed turbulent flow of a shear thinning fluid (n=0.75) in a stationary pipe at a simulation's Reynolds number equals…

Fluid Dynamics · Physics 2020-06-01 Mohamed Abdi , Meryem Ould-Rouiss , Abdelkader Noureddine

The magnetorotational (MRI) dynamo has long been considered one of the possible drivers of turbulent angular momentum transport in astrophysical accretion disks. However, various numerical results suggest that this dynamo may be difficult…

High Energy Astrophysical Phenomena · Physics 2015-02-12 A. Riols , F. Rincon , C. Cossu , G. Lesur , G. I. Ogilvie , P-Y. Longaretti

We present a scaling law that predicts the values of the stresses obtained in numerical simulations of saturated MRI-driven turbulence in non-stratified shearing boxes. It relates the turbulent stresses to the strength of the vertical…

Astrophysics · Physics 2009-11-13 Martin E. Pessah , Chi-kwan Chan , Dimitrios Psaltis

From numerical simulations, we show that non-rotating magnetohydrodynamic shear flows are unstable to finite amplitude velocity perturbations and become turbulent, leading to the growth and sustenance of magnetic energy, including large…

Plasma Physics · Physics 2017-03-10 Farrukh Nauman , Eric G. Blackman

We present a systematic analysis of statistical properties of turbulent current and vorticity structures at a given time using cluster analysis. The data stems from numerical simulations of decaying three-dimensional (3D)…

Fluid Dynamics · Physics 2013-05-29 Vadim M. Uritsky , Annick Pouquet , Duane Rosenberg , Pablo D. Mininni , Eric Donovan

It is demonstrated that the azimuthal magnetorotational instability (AMRI) also works with radially increasing rotation rates contrary to the standard magnetorotational instability for axial fields which requires negative shear. The…

Fluid Dynamics · Physics 2017-12-14 Guenther Rüdiger , Manfred Schultz , Marcus Gellert , Frank Stefani

Understanding the interaction mechanisms between large-scale magnetohydrodynamic instabilities and small-scale drift-wave microturbulence is essential for predicting and optimizing the performance of magnetic confinement based fusion energy…

Plasma Physics · Physics 2016-09-14 Olivier Izacard , Christopher Holland , Spencer D. James , Dylan P. Brennan

We studied Faraday rotation measure (RM) in turbulent media with the rms Mach number of unity, using isothermal, magnetohydrodynamic turbulence simulations. Four cases with different values of initial plasma beta were considered. Our main…

Astrophysics of Galaxies · Physics 2014-11-20 Qingwen Wu , Jongsoo Kim , Dongsu Ryu , Jungyeon Cho , Paul Alexander

A wide variety of astrophysical phenomena involve the flow of turbulent magnetized gas with relativistic velocity or energy density. Examples include gamma-ray bursts, active galactic nuclei, pulsars, magnetars, micro-quasars, merging…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Jonathan Zrake , Andrew MacFadyen

Numerical simulations of the magnetorotational instability (MRI) with zero initial net flux in a non-stratified isothermal cubic domain are used to demonstrate the importance of magnetic boundary conditions.In fully periodic systems the…

High Energy Astrophysical Phenomena · Physics 2011-07-08 Petri J. Käpylä , Maarit J. Korpi

We carry out a comprehensive analysis of the behavior of the magnetorotational instability (MRI) in viscous, resistive plasmas. We find exact, non-linear solutions of the non-ideal magnetohydrodynamic (MHD) equations describing the local…

Astrophysics · Physics 2009-11-13 Martin E. Pessah , Chi-kwan Chan

Statistical properties of turbulent Rayleigh-Benard convection at low Prandtl numbers (Pr), which are typical for liquid metals such as mercury, gallium or liquid sodium, are investigated in high-resolution three-dimensional spectral…

Fluid Dynamics · Physics 2016-09-13 Janet D. Scheel , Joerg Schumacher

Turbulence in a conducting plasma can amplify seed magnetic fields in what is known as the turbulent, or small-scale, dynamo. The associated growth rate and emergent magnetic-field geometry depend sensitively on the material properties of…

High Energy Astrophysical Phenomena · Physics 2022-10-17 Alisa K. Galishnikova , Matthew W. Kunz , Alexander A. Schekochihin

The intermittent small-scale structure of turbulence governs energy dissipation in many astrophysical plasmas and is often believed to have universal properties for sufficiently large systems. In this work, we argue that small-scale…

High Energy Astrophysical Phenomena · Physics 2017-03-22 Vladimir Zhdankin , Justin Walker , Stanislav Boldyrev , Geoffroy Lesur