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Related papers: Oscillatory migrating magnetic fields in helical t…

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We present the results of simulations of forced turbulence in a slab where the mean kinetic helicity has a maximum near the mid-plane, generating gradients of magnetic helicity of both large and small-scale fields. We also study systems…

Solar and Stellar Astrophysics · Physics 2010-11-30 A. Hubbard , A. Brandenburg

The degree of linear polarization has recently been found to show wide random variations over the solar disk. These variations are presumably at least partly due to fluctuations in the flux density of turbulent photospheric magnetic fields…

Astrophysics · Physics 2007-05-23 K. Petrovay

We show that oppositely directed fluxes of energy and magnetic helicity coexist in the inertial range in fully developed magnetohydrodynamic (MHD) turbulence with small-scale sources of magnetic helicity. Using a helical shell model of MHD…

Plasma Physics · Physics 2015-06-23 Rodion Stepanov , Peter Frick , Irina Mizeva

Convection in rotating spherical geometries is an important physical process in planetary and stellar systems. Using continuation methods at low Prandtl number, we find both strong equatorially asymmetric and symmetric polar nonlinear…

Solar and Stellar Astrophysics · Physics 2019-07-17 F. Garcia , F. R. N. Chambers , A. L. Watts

The ohmic decay of magnetic fields in the crusts of neutron stars is generally believed to be governed by Hall drift which leads to what is known as a Hall cascade. Here we show that helical and fractionally helical magnetic fields undergo…

High Energy Astrophysical Phenomena · Physics 2020-09-18 Axel Brandenburg

It is shown that helicity dynamics dominates spectral distribution of the velocity fluctuations in turbulent thermal convection at moderate and large values of the Rayleigh number (distributed chaos and scaling respectively). The…

Fluid Dynamics · Physics 2020-04-29 A. Bershadskii

It is shown that incompressible spin quantum Hall magnetohydrodynamics allows an exact solution for the propagation of a circularly polarized electromagnetic wave. The solution is obtained assuming a condition between the fluid velocity and…

Plasma Physics · Physics 2010-10-19 Felipe A. Asenjo

Convective dynamo simulations are performed in local Cartesian geometry. We report the first successful simulation of a large-scale oscillatory dynamo in rigidly rotating convection without stably stratified layers. A key requirement for…

Solar and Stellar Astrophysics · Physics 2015-06-19 Youhei Masada , Takayoshi Sano

Measurements made with the Voyager 1 spacecraft indicate that significant levels of compressive fluctuations exist in the inner heliosheath. Some studies have already been performed with respect to the mirror-mode instability in the…

We present three-dimensional nonlinear magnetohydrodynamic simulations of the interiors of fully convective M-dwarfs. Our models consider 0.3 solar-mass stars using the Anelastic Spherical Harmonic code, with the spherical computational…

Astrophysics · Physics 2009-11-13 Matthew Browning

We present new simulations of decaying hydromagnetic turbulence for a relativistic equation of state relevant to the early universe. We compare helical and nonhelical cases either with kinetically or magnetically dominated initial fields.…

Cosmology and Nongalactic Astrophysics · Physics 2017-12-29 Axel Brandenburg , Tina Kahniashvili , Sayan Mandal , Alberto Roper Pol , Alexander G. Tevzadze , Tanmay Vachaspati

Helical magnetic background fields with adjustable pitch angle are imposed on a conducting fluid in a differentially rotating cylindrical container. The small-scale kinetic and current helicities are calculated for various field geometries,…

Solar and Stellar Astrophysics · Physics 2015-05-20 M. Gellert , G. Ruediger , R. Hollerbach

The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional…

When magnetohydrodynamic turbulence evolves in the presence of a large-scale mean magnetic field, an anisotropy develops relative to that preferred direction. The well-known tendency is to develop stronger gradients perpendicular to the…

Plasma Physics · Physics 2020-07-15 Rohit Chhiber , William H. Matthaeus , Sean Oughton , Tulasi N. Parashar

The free decay of MHD turbulence at large Reynolds numbers is studied numerically using a shell model. We study the statistical properties based on representative sample of realisations (128 realisations for each type of initial conditions)…

Fluid Dynamics · Physics 2010-09-23 Peter Frick , Rodion Stepanov

We study rotating thermal convection in spherical shells. We base our analysis on a set of about 450 direct numerical simulations of the (magneto)hydrodynamic equations under the Boussinesq approximation. The Ekman number ranges from…

Earth and Planetary Astrophysics · Physics 2016-01-20 Rakesh K. Yadav , Thomas Gastine , Ulrich R. Christensen , Lucia Duarte , Ansgar Reiners

We study the inverse cascade of magnetic helicity in conducting fluids by investigating the detailed transfer of helicity between different spherical shells in Fourier space in direct numerical simulations of three-dimensional…

Plasma Physics · Physics 2009-11-11 Alexandros Alexakis , Pablo Mininni , Annick Pouquet

Mars Global Surveyor measurements revealed that the Martian crust is strongly magnetized in the southern hemisphere while the northern hemisphere is virtually void of magnetization. Two possible reasons have been suggested for this…

Earth and Planetary Astrophysics · Physics 2014-02-04 Wieland Dietrich , Johannes Wicht

Some observations suggest that solar spicules show small amplitude and high frequency oscillations of magneto-acoustic waves, which arise from photospheric granular forcing. We apply the method of MHD seismology to determine the period of…

Astrophysics · Physics 2009-11-13 A. Ajabshirizadeh , E. Tavabi , S. Koutchmy

Motivated by recent analytic predictions, we report numerical evidence showing that in driven incompressible magnetohydrodynamic turbulence the magnetic- and velocity-field fluctuations locally tend to align the directions of their…

Astrophysics · Physics 2007-05-23 Joanne Mason , Fausto Cattaneo , Stanislav Boldyrev