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We present 3-d numerical magneto-hydrodynamic simulations of a buoyant, twisted magnetic flux rope embedded in a stratified, solar-like model convection zone. The flux rope is given an initial twist such that it neither kinks nor fragments…

Astrophysics · Physics 2009-11-07 S. B. F. Dorch , B. V. Gudiksen , W. P. Abbett , Aa. Nordlund

Convection of an internally heated fluid, confined between top and bottom plates of equal temperature, is studied by direct numerical simulation in two and three dimensions. The unstably stratified upper region drives convection that…

Fluid Dynamics · Physics 2016-06-30 David Goluskin , Erwin P. van der Poel

An oblique pulsar magnetosphere with a plasma conductivity is studied by using a pseudo-spectral method. In the pseudo-spectral method, the time-dependent Maxwell equations are solved, both electric and magnetic fields are expanded in terms…

High Energy Astrophysical Phenomena · Physics 2016-07-27 Gang Cao , Li Zhang , Sineng Sun

In-situ observations in the Earth's and Saturn's magnetosheaths and in the solar wind reveal the presence of Alfv\'en vortices as intermittent structures in the range of scales from fluid lengths down to few ion lengths. The density and the…

Plasma Physics · Physics 2020-04-16 Dusan Jovanovic , Olga Alexandrova , Milan Maksimovic , Milivoj Belic

A self-consistent model is presented for performing steady-state fully kinetic Particle-in-Cell simulations of magnetised plasma plumes. An energy-based electron reflection prevents the numerical pump instability associated with a typical…

Plasma Physics · Physics 2022-02-23 Shaun Andrews , Simone Di Fede , Mirko Magarotto

Recent pulsed-power experiments have demonstrated the formation of astrophysically-relevant, differentially rotating plasmas [1]. Key features of the plasma flows are the discovery of a quasi-Keplerian rotation curve, the launching of…

We present the first self-consistent global simulations of pulsar magnetospheres with operating $e^\pm$ discharge. We focus on the simple configuration of an aligned or anti-aligned rotator. The star is spun up from zero (vacuum) state to a…

High Energy Astrophysical Phenomena · Physics 2014-10-28 Alexander Y. Chen , Andrei M. Beloborodov

We study rotating homogeneous turbulent convection forced by a mean vertical temperature gradient by means of direct numerical simulations (DNS) in the Boussinesq approximation in a rotating frame. In the absence of rotationour results are…

Fluid Dynamics · Physics 2019-10-30 Francesco Toselli , Stefano Musacchio , Guido Boffetta

We present a comprehensive radiative magnetohydrodynamic simulation of the quiet Sun and large solar active regions. The 197 Mm wide simulation domain spans from 18 (10) Mm beneath the photosphere to 113 Mm in the solar corona. Radiative…

Solar and Stellar Astrophysics · Physics 2022-10-12 Feng Chen , Matthias Rempel , Yuhong Fan

The paper presents a study of kinematic axisymmetric mean-field dynamo models for a case of the meridional circulation with a deep-seated stagnation point and a strong return flow at the bottom of the convection zone. This kind of…

Solar and Stellar Astrophysics · Physics 2015-05-27 V. V. Pipin , A. G. Kosovichev

Thermal convection is observed in molecular dynamic simulation of a fluidized granular system of nearly elastic hard disks moving under gravity, inside a rectangular box. Boundaries introduce no shearing or time dependence, but the energy…

Statistical Mechanics · Physics 2009-10-31 Rosa Ramirez , Dino Risso , Patricio Cordero

The stationary axisymmetric force-free magnetosphere of a pulsar is studied analytically. The pulsar equation is solved in the region close to the magnetic axis. Proceeding from linearization of the current function in the axial region, we…

High Energy Astrophysical Phenomena · Physics 2015-06-11 S. A. Petrova

Observations reveal that strong solar flares and coronal mass ejections tend to occur in complex active regions characterized by delta-sunspots, spot rotation, sheared polarity inversion lines (PILs), and magnetic flux ropes. Here we report…

Solar and Stellar Astrophysics · Physics 2019-12-11 Shin Toriumi , Hideyuki Hotta

The axisymmetric 3-D MHD outflow of a cold plasma from a magnetized and rotating astrophysical object is numerically simulated with the purpose of investigating the outflow's magnetocentrifugal acceleration and eventual collimation. Gravity…

Astrophysics · Physics 2009-10-31 S. Bogovalov , K. Tsinganos

We reinvestigate the generation and accumulation of magnetic flux in optically thin accretion flows around active gravitating objects. The source of the magnetic field is the azimuthal electric current associated with the Poynting-Robertson…

Asymmetric current sheets are likely to be prevalent in both astrophysical and laboratory plasmas with complex three dimensional (3D) magnetic topologies. This work presents kinematic analytical models for spine and fan reconnection at a…

Plasma Physics · Physics 2013-06-28 Peter F Wyper , Rekha Jain

We present results from the first 3D kinetic numerical simulation of magnetorotational turbulence and dynamo, using the local shearing-box model of a collisionless accretion disc. The kinetic magnetorotational instability grows from a…

High Energy Astrophysical Phenomena · Physics 2016-12-07 Matthew W. Kunz , James M. Stone , Eliot Quataert

Recent high resolution observations by the {\it Chandra} X-ray satellite revealed various substructures in hot X-ray emitting plasmas in cluster of galaxies. For example, {\it Chandra} revealed the existence of sharp discontinuities in the…

Astrophysics · Physics 2009-11-11 Naoki Asai , Naoya Fukuda , Ryoji Matsumoto

The latitudinal distribution of starspots deviates from the solar pattern with increasing rotation rate. Numerical simulations of magnetic flux emergence and transport can help model the observed stellar activity patterns and the associated…

Solar and Stellar Astrophysics · Physics 2018-12-19 Emre Işık , Sami K. Solanki , Natalie A. Krivova , Alexander I. Shapiro

We present the results of three-dimensional numerical simulations to investigate the excitation of waves in the magnetic network of the Sun due to footpoint motions of a magnetic flux tube. We consider motions that typically mimic granular…

Solar and Stellar Astrophysics · Physics 2015-06-15 G. Vigeesh , S. S. Hasan