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(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…

Astrophysics · Physics 2009-07-29 P. J. Käpylä , M. J. Korpi , A. Brandenburg

We investigate magnetohydrodynamic (MHD) turbulence in plane shear flows with a streamwise background magnetic field in the super-Alfv\'enic regime. We show that the large-scale velocity shear suppresses turbulence imbalance, driving the…

Space Physics · Physics 2026-02-17 M. Kavtaradze , G. Mamatsashvili , G. Chagelishvili , E. Uchava

Fluid discontinuities, such as shock fronts and vortex sheets, can reflect waves and become unstable to corrugation. Analytical calculations of these phenomena are tractable in the simplest cases only, while their numerical simulations are…

Plasma Physics · Physics 2023-08-16 William Béthune

The generation of turbulence at magnetized shocks and its subsequent interaction with the latter is a key question of plasma- and high-energy astrophysics. This paper presents two-dimensional magnetohydrodynamic simulations of a fast shock…

High Energy Astrophysical Phenomena · Physics 2018-01-09 Camilia Demidem , Martin Lemoine , Fabien Casse

It is shown that the use of a high power $\alpha$ of the Laplacian in the dissipative term of hydrodynamical equations leads asymptotically to truncated inviscid \textit{conservative} dynamics with a finite range of spatial Fourier modes.…

Aims: To determine alpha effect and turbulent magnetic diffusivity for mean magnetic fields with profiles of different length scale from simulations of isotropic turbulence, and to relate these results to nonlocal formulations in which…

Astrophysics · Physics 2008-04-30 A. Brandenburg , K. -H. Rädler , M. Schrinner

Dynamo action owing to helically forced turbulence and large-scale shear is studied using direct numerical simulations. The resulting magnetic field displays propagating wave-like behavior. This behavior can be modelled in terms of an…

Astrophysics · Physics 2011-02-11 P. J. Käpylä , A. Brandenburg

Following the previous work of Ferretti and Yang on the role of magnetic fields in the theory of conformal turbulence, we show that non-unitary minimal model solutions to 2-dimensional magnetohydrodynamics (MHD) obtained by dimensional…

High Energy Physics - Theory · Physics 2015-06-26 Omduth Coceal , Steven Thomas

We present a set of three-dimensional (3D) direct numerical simulations of incompressible decaying magnetohydrodynamic turbulence in which we investigate the influence of an external uniform magnetic field B_0. A parametric study in terms…

Fluid Dynamics · Physics 2009-11-13 Barbara Bigot , Sebastien Galtier , Helene Politano

This manuscript has been accepted for publication in Physical Review Fluids, see https://journals.aps.org/prfluids/accepted/d5074S28J6b11905012b7cb06505e8f2149dd5f20. This work investigates the mechanisms that underlie transitions to…

Fluid Dynamics · Physics 2020-12-24 Christopher J. Camobreco , Alban Pothérat , Gregory J. Sheard

Lagrangian turbulence lies at the core of numerous applied and fundamental problems related to the physics of dispersion and mixing in engineering, bio-fluids, atmosphere, oceans, and astrophysics. Despite exceptional theoretical,…

Various approaches to estimate turbulent transport coefficients from numerical simulations of hydromagnetic turbulence are discussed. A quantitative comparison between the averaged magnetic field obtained from a specific three-dimensional…

Astrophysics · Physics 2009-11-07 Axel Brandenburg , Dmitry Sokoloff

Turbulence in the magnetized plasma is well understood to be the consequence of wave interactions. When the Hall effect is added to the minimum magnetohydrodynamics (MHD), the MHD waves become dispersive and different nonlinear interactions…

Plasma Physics · Physics 2026-02-19 Erik C. Hansen , Prerana Sharma , Swadesh M. Mahajan

We begin by placing the Generalized Lagrangian Mean (GLM) equations for a compressible adiabatic fluid into the Euler-Poincar\'e (EP) variational framework of fluid dynamics, for an averaged Lagrangian. We then derive a set of approximate…

Chaotic Dynamics · Physics 2015-06-26 Darryl D. Holm

It is well known that the nonlinear evolution of magnetohydrodynamic (MHD) turbulence generates current sheets. In the solar wind turbulence, current sheets are frequently observed and they are believed to be an important pathway for the…

Solar and Stellar Astrophysics · Physics 2026-03-19 Chen Shi , Marco Velli , Nikos Sioulas , Zijin Zhang

The properties of linear Alfv\'en, slow, and fast magnetoacoustic waves for uniform plasmas in relativistic magnetohydrodynamics (MHD) are discussed, augmenting the well-known expressions for their phase speeds with knowledge on the group…

Astrophysics · Physics 2008-10-15 R. Keppens , Z. Meliani

In this review article we will describe recent developments in statistical theory of magnetohydrodynamic (MHD) turbulence. Kraichnan and Iroshnikov first proposed a phenomenology of MHD turbulence where Alfven time-scale dominates the…

Chaotic Dynamics · Physics 2009-11-10 Mahendra K. Verma

Compressible turbulence, especially the magnetized version of it, traditionally has a bad reputation with researchers. However, recent progress in theoretical understanding of incompressible MHD as well as that in computational capabilities…

Astrophysics · Physics 2007-05-23 Jungyeon Cho , A. Lazarian

The Magneto-Hydrodynamic (MHD) system of equations governs viscous fluids subject to a magnetic field and is derived via a coupling of the Navier-Stokes equations and Maxwell's equations. Recently it has become common to study…

Analysis of PDEs · Mathematics 2020-05-29 Lorenzo Riva , Nathan Pennington

We analyze 3D numerical simulations of driven incompressible magnetohydrodynamic (MHD) turbulence in a periodic box threaded by a moderately strong external magnetic field. We sum over nonlinear interactions within Fourier wavebands and…

Astrophysics · Physics 2011-05-10 Jungyeon Cho , Alex Lazarian , Ethan Vishniac
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