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In many astrophysical plasmas, the Coulomb collision is insufficient to maintain an isotropic temperature, and the system is driven to the anisotropic regime. In this case, magnetohydrodynamic (MHD) models with anisotropic pressure are…

Plasma Physics · Physics 2023-08-09 Hongyang Luo , John G. Lyon , Binzheng Zhang

The Magneto-hydrodynamic (MHD) equations in the presence of a guiding magnetic field are investigated by means of direct numerical simulations. The basis of the investigation consists of 9 runs forced at the small scales. The results…

Fluid Dynamics · Physics 2015-05-30 Alexandros Alexakis

A description is given for preserving ${\bmsy\nabla}\cdot{\vec B}=0$ in a magnetohydrodynamic (MHD) code that employs the upwind, Total Variation Diminishing (TVD) scheme and the Strang-type operator splitting for multi-dimensionality. The…

Astrophysics · Physics 2009-10-30 Dongsu Ryu , Francesco Miniati , T. W. Jones , Adam Frank

The impressive progress of the kinetic schemes in the solution of gas dynamics problems and the development of effective parallel algorithms for modern high performance parallel computing systems led to the development of advanced methods…

Plasma Physics · Physics 2013-05-06 B. Chetverushkin , N. D'Ascenzo , V. Saveliev

The ideal invariants present in the formalism of magnetohydrodynamics (MHD), i.e. global quantities that are conserved in the absence of sources and dissipative effects, play an important role in various theoretical and numerical studies of…

Fluid Dynamics · Physics 2011-08-15 B. Teaca , C. C. Lalescu , B. Knaepen , D. Carati

We present a meshless method for magnetohydrodynamics by evolving the vector potential of magnetic fields. A novel scheme and numerical techniques are developed to restrict the divergence of magnetic field, based on the Meshless Finite…

Instrumentation and Methods for Astrophysics · Physics 2022-09-28 Xiongbiao Tu , Qiao Wang , Haonan Zheng , Liang Gao

We test a new "hybrid" scheme for simulating dynamical fluid flows in which cylindrical components of the momentum are advected across a rotating Cartesian coordinate mesh. This hybrid scheme allows us to conserve angular momentum to…

Solar and Stellar Astrophysics · Physics 2015-06-19 Zachary D. Byerly , Bryce Adelstein-Lelbach , Joel E. Tohline , Dominic C. Marcello

In this chapter, we aim at presenting the basic techniques necessary to go beyond the widely accepted paradigm of second-order numerics. We specifically focus on finite-volume schemes for hyperbolic conservation laws occuring in fluid…

Numerical Analysis · Mathematics 2024-07-29 Jean-Mathieu Teissier , Wolf-Christian Müller

In certain astrophysical systems the commonly employed ideal magnetohydrodynamics (MHD) approximation breaks down. Here, we introduce novel explicit and implicit numerical schemes of ohmic resistivity terms in the moving-mesh code AREPO. We…

Instrumentation and Methods for Astrophysics · Physics 2018-03-09 Federico Marinacci , Mark Vogelsberger , Rahul Kannan , Philip Mocz , Rüdiger Pakmor , Volker Springel

Numerical methods to improve the treatment of magnetic fields in smoothed field magnetohydrodynamics (SPMHD) are developed and tested. Chapter 2 is a review of SPMHD. In Chapter 3, a mixed hyperbolic/parabolic scheme is developed which…

Instrumentation and Methods for Astrophysics · Physics 2015-05-19 Terrence S. Tricco

Due to the prevalence of magnetic fields in astrophysical environments, magnetohydrodynamic (MHD) simulation has become a basic tool for studying astrophysical fluid dynamics. To further advance the precision of MHD simulations, we have…

High Energy Astrophysical Phenomena · Physics 2023-08-09 Jeongbhin Seo , Dongsu Ryu

FISH is a fast and simple ideal magneto-hydrodynamics code that scales to ~10 000 processes for a Cartesian computational domain of ~1000^3 cells. The simplicity of FISH has been achieved by the rigorous application of the operator…

Instrumentation and Methods for Astrophysics · Physics 2011-08-11 R. Kaeppeli , S. C. Whitehouse , S. Scheidegger , U. -L. Pen , M. Liebendoerfer

We describe a numerical method to solve the magnetohydrodynamic (MHD) equations. The fluid variables are updated along each direction using the flux conservative, 2nd order, total variation diminishing (TVD), upwind scheme of Jin and Xin.…

Astrophysics · Physics 2015-06-24 Ue-Li Pen , Phil Arras , ShingKwong Wong

Numerical methods for solving the ideal magnetohydrodynamic (MHD) equations in more than one space dimension must confront the challenge of controlling errors in the discrete divergence of the magnetic field. One approach that has been…

Numerical Analysis · Mathematics 2012-10-16 Christiane Helzel , James A. Rossmanith , Bertram Taetz

Dimensionally split advection schemes are attractive for atmospheric modelling due to their efficiency and accuracy in each spatial dimension. Accurate long time-steps can be achieved without significant cost using the flux-form…

Numerical Analysis · Mathematics 2017-01-25 Yumeng Chen , Hilary Weller , Stephen Pring , James Shaw

We present a new multi-dimensional, robust, and cell-centered finite-volume scheme for the ideal MHD equations. This scheme relies on relaxation and splitting techniques and can be easily used at high order. A fully conservative version is…

We modify an existing magnetohydrodynamics algorithm to make it more compatible with a dimensionally-split (DS) framework. It is based on the standard reconstruct-solve-average strategy (using a Riemann solver), and relies on constrained…

Instrumentation and Methods for Astrophysics · Physics 2013-05-17 Hari Sriskantha , Maximilian Ruffert

Using a new numerical code we have carried out two-dimensional simulations of the nonlinear evolution of unstable sheared magnetohydrodynamic flows. We considered two cases: a strong magnetic field (Alfven Mach number, M_a = 2.5) and a weak…

Astrophysics · Physics 2009-10-28 Adam Frank , T. W. Jones , Dongsu Ryu , Joseph B. Gaalaas

Newcomb's Lagrangian for ideal magnetohydrodynamics (MHD) in Lagrangian labeling is discretized using discrete exterior calculus. Variational integrators for ideal MHD are derived thereafter. Besides being symplectic and…

Plasma Physics · Physics 2014-10-27 Yao Zhou , Hong Qin , J. W. Burby , A. Bhattacharjee

We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a…

Solar and Stellar Astrophysics · Physics 2015-06-15 Glenn E. Ciolek , Wayne G. Roberge