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A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modelled analytically, within a realistic stratified atmosphere subject to solar gravity. This extends results for a single magnetic flux tube…

Solar and Stellar Astrophysics · Physics 2014-07-18 Frederick A. Gent , Viktor Fedun , Rebertus Erd'elyi

Axisymmetric steady-state weakly ionized Hall-MHD Keplerian thin disks are investigated by using asymptotic expansions in the small disk aspect ratio \epsilon. The model incorporates the azimuthal and poloidal components of the magnetic…

Astrophysics · Physics 2015-05-27 Yuri M. Shtemler , Michael Mond , Gunther Rudiger

The present paper reviews recent advances in the theory of nonlinear driven magnetohydrodynamic (MHD) waves in slow and Alfven resonant layers. Simple estimations show that in the vicinity of resonant positions the amplitude of variables…

Solar and Stellar Astrophysics · Physics 2015-05-20 Istvan Ballai , Michael Ruderman

Given a tetrahedral mesh and objective functionals measuring the mesh quality which take into account the shape, size, and orientation of the mesh elements, our aim is to improve the mesh quality as much as possible. In this paper, we…

Numerical Analysis · Mathematics 2018-06-29 Franco Dassi , Lennard Kamenski , Patricio Farrell , Hang Si

Axisymmetric equilibria with incompressible flows of arbitrary direction are studied in the framework of magnetohydrodynamics under a variety of physically relevant side conditions. To this end a set of pertinent non-linear ODEs are…

Plasma Physics · Physics 2007-05-23 G. N. Throumoulopoulos , H. Tasso , G. Poulipoulis

We provide compelling numerical evidence for the development of (potential) finite-time singularities in the three-dimensional (3D) axisymmetric, ideal, incompressible magnetohydrodynamic (IMHD) equations, in a wall-bounded cylindrical…

Fluid Dynamics · Physics 2025-07-10 Venkata Sai Swetha Kolluru , Rahul Pandit

Smoothed particle magnetohydrodynamics has reached a level of maturity that enables the study of a wide range of astrophysical problems. In this review, the numerical details of the modern SPMHD method are described. The three fundamental…

Instrumentation and Methods for Astrophysics · Physics 2023-11-27 Terrence S. Tricco

The tearing mode instability is a key process for magnetic energy conversion in magnetohydrodynamics, once anti-parallel components are allowed to reconnect, leading to the formation of magnetic islands. It has been employed to explain…

Solar and Stellar Astrophysics · Physics 2024-07-16 Grzegorz Kowal , Diego A. Falceta-Gonçalves

Models of magnetohydrodynamic (MHD) equilibia that for computational convenience assume the existence of a system of nested magnetic flux surfaces tend to exhibit singular current sheets. These sheets are located on resonant flux surfaces…

Plasma Physics · Physics 2020-04-22 Eugenia Kim , Geoffrey McFadden , Antoine Cerfon

The present study is a continuation of a previous one on "hyperelliptic" axisymmetric equilibria started in [Tasso and Throumoulopoulos, Phys. Plasmas 5, 2378 (1998)]. Specifically, some equilibria with incompressible flow nonaligned with…

Plasma Physics · Physics 2009-11-10 H. Tasso , G. N. Throumoulopoulos

We describe a high-order numerical magnetohydrodynamics (MHD) solver built upon a novel non-linear entropy stable numerical flux function that supports eight travelling wave solutions. By construction the solver conserves mass, momentum,…

Astrophysics of Galaxies · Physics 2016-05-13 Dominik Derigs , Andrew R. Winters , Gregor J. Gassner , Stefanie Walch

We extend the theory for third-order structure functions in homogeneous incompressible magnetohydrodynamic (MHD) turbulence to the case in which a constant velocity shear is present. A generalization is found of the usual relation [Politano…

Plasma Physics · Physics 2015-05-13 M. Wan , S. Servidio , S. Oughton , W. H. Matthaeus

Quasisymmetry (QS), a hidden symmetry of the magnetic field strength, is known to support nested flux surfaces and provide superior particle confinement in stellarators. In this work, we study the ideal MHD equilibrium and stability of…

Plasma Physics · Physics 2024-02-06 W. Sengupta , N. Nikulsin , R. Gaur , A. Bhattacharjee

In three dimensional toroidal domains without symmetry, the standard magnetohydrodynamic (MHD) equilibrium model used for magnetic confinement fusion does not generally support smooth solutions. Instead, solutions have singular plasma…

Plasma Physics · Physics 2026-04-13 Maximilian Ruth , Joshua W. Burby , Wrick Sengupta , Andrew Brown

Being motivated by the paper [O. I. Bogoyavlenskij, Phys. Rev. 66, 056410 (2002)] we generalise the symmetry transformations for MHD equilibria with isotropic pressure and incompressible flow parallel to the magnetic field introduced…

Plasma Physics · Physics 2019-07-24 A. Evangelias , G. N. Throumoulopoulos

We numerically study the evolution of magnetic fields and fluid flows in a thin spherical shell. We take the initial field to be a latitudinally confined, predominantly toroidal flux tube. For purely toroidal, untwisted flux tubes, we…

Solar and Stellar Astrophysics · Physics 2009-12-29 R. Hollerbach , P. S. Cally

We study semi-analytical time-dependent solutions of the relativistic magnetohydrodynamic (MHD) equations for the fields and the fluid emerging from a spherical source. We assume uniform expansion of the field and the fluid and a polytropic…

High Energy Astrophysical Phenomena · Physics 2010-09-30 K. N. Gourgouliatos , N. Vlahakis

A simplified analytical form of the on-axis magnetic well and Mercier's criterion for interchange instabilities for arbitrary three-dimensional magnetic field geometries is derived. For this purpose, a near-axis expansion based on a direct…

Plasma Physics · Physics 2021-05-12 Patrick Kim , Rogerio Jorge , William Dorland

Self-consistent, one-dimensional quasineutral screw-pinch equilibria are constructed within a hybrid model that couples fluid electrons with kinetic ions governed by the Vlasov equation. The equilibria depend on the radial coordinate…

Plasma Physics · Physics 2025-07-29 D. A. Kaltsas , A. I. Kuiroukidis , G. N. Throumoulopoulos

The three-dimensional nature of plasmoid instabilities is studied using the reduced magnetohydrodynamic equations. For a Harris equilibrium with guide field, represented by $\vc{B}_o = B_{po} \tanh (x/\lambda) \hat{y} + B_{zo} \hat{z}$, a…

Plasma Physics · Physics 2015-06-03 S. D. Baalrud , A. Bhattacharjee , Y. -M. Huang