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We describe a numerical code to solve the equations for ideal magnetohydrodynamics (MHD). It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a…

Astrophysics · Physics 2009-10-22 Dongsu Ryu , T. W. Jones

In two previous papers (Price & Monaghan 2004a,b) (papers I,II) we have described an algorithm for solving the equations of Magnetohydrodynamics (MHD) using the Smoothed Particle Hydrodynamics (SPH) method. The algorithm uses dissipative…

Astrophysics · Physics 2009-11-13 D. J. Price , J. J. Monaghan

We present an investigation on effect of the ion-neutral (or ambipolar) diffusion heating rate on thermal phases of a molecular cloud. We use the modeling of ambipolar diffusion with two-fluid smoothed particle hydrodynamics, as discussed…

Astrophysics · Physics 2008-04-29 M. Nejad-Asghar , D. Molteni

Ambipolar diffusion (AD) is believed to be a crucial process for redistributing magnetic flux in the dense molecular gas that occurs in regions of star formation. We carry out numerical simulations of this process in regions of low…

Solar and Stellar Astrophysics · Physics 2015-05-30 Pak Shing Li , Christopher F. McKee , Richard I. Klein

Maxwell equations are solved in a layer comprising a finite number of homogeneous isotropic dielectric regions ended by anisotropic perfectly matched layers (PMLs). The boundary-value problem is solved and the dispersion relation inside the…

Optics · Physics 2009-11-10 Diana C. Skigin

Given the importance of simulating hydromagnetic processes that impact star formation, we have earlier developed a 3D adaptive mesh approach that allows us to include hydromagnetic processes during the formation and evolution of cores,…

Astrophysics · Physics 2009-11-13 D. F. Duffin , R. E. Pudritz

We describe a Godunov-type magnetohydrodynamic (MHD) code based on the Miyoshi and Kusano (2005) solver which can be used to solve various astrophysical hydrodynamic and MHD problems. The energy equation is in the form of entropy…

Astrophysics of Galaxies · Physics 2015-12-16 A. V. Koldoba , G. V. Ustyugova , P. S. Lii , M. L. Comins , S. Dyda , M. M. Romanova , R. V. E. Lovelace

We numerically reproduce the density profiles for filaments that are in magnetohydrostatic and pressure equilibrium with their surroundings obtained in Tomisaka (2014) and show that these equilibria are dynamically stable. If the effect of…

Astrophysics of Galaxies · Physics 2016-11-30 C. A. Burge , S. Van Loo , S. A. E. G. Falle , T. W. Hartquist

We study the effect of the non-linear process of ambipolar diffusion (joint transport of magnetic flux and charged particles relative to neutral particles) on the long-term behavior of a non-uniform magnetic field in a one-dimensional…

Solar and Stellar Astrophysics · Physics 2015-05-18 Jaime Hoyos , Andreas Reisenegger , Juan Valdivia

Ambipolar diffusion is important in redistributing magnetic flux and in damping Alfven waves in molecular clouds. The importance of ambipolar diffusion on a length scale $\ell$ is governed by the ambipolar diffusion Reynolds number,…

Solar and Stellar Astrophysics · Physics 2015-05-19 Christopher F. McKee , Pak Shing Li , Richard I. Klein

We study the self-similar magnetohydrodynamics (MHD) of a quasi-spherical expanding void (viz. cavity or bubble) in the centre of a self-gravitating gas sphere with a general polytropic equation of state. We show various analytic asymptotic…

Astrophysics of Galaxies · Physics 2009-11-09 Yu-Qing Lou , Ren-Yu Hu

Magnetic fields play a role in the dynamics of many astrophysical processes, but they are hard to detect. In a partially ionized plasma, a magnetic field works directly on the ionized medium but not on the neutral medium, which gives rise…

Solar and Stellar Astrophysics · Physics 2020-06-24 Boy Lankhaar , Wouter Vlemmings

In this paper, using the approximate particular solutions of Helmholtz equations, we solve the boundary value problems of Helmholtz equations by combining the methods of fundamental solutions (MFS) with the methods of particular solutions…

Numerical Analysis · Mathematics 2024-11-27 Adam Johnson

Especially in cold and high-density regions, the assumptions of ideal magnetohydrodynamics (MHD) can break down, making first order non-ideal terms such as Ohmic and ambipolar diffusion as well as the Hall effect important. In this study we…

Earth and Planetary Astrophysics · Physics 2023-07-25 Oliver Zier , Volker Springel , Alexander C. Mayer

We investigate the jet launching process from accretion disks extending our recent study (paper I) to a truly bipolar setup. We perform axisymmetric MHD simulations of the disk-jet interaction on a computational domain covering both…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Christian Fendt , Somayeh Sheikhnezami

The aim of this paper is to improve our understanding of the heating mechanisms of the solar chromosphere via realistic three-dimensional (3D) modeling of solar magneto-convection, considering the fact that solar plasma contains a…

Solar and Stellar Astrophysics · Physics 2025-05-07 E. Khomenko , N. Vitas , M. Collados , M. Modestov

It is generally believed that turbulence has a significant impact on the dynamics and evolution of molecular clouds and the star formation which occurs within them. Non-ideal magnetohydrodynamic effects are known to influence the nature of…

Astrophysics of Galaxies · Physics 2015-03-17 Turlough P. Downes , Stephen O'Sullivan

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

The interaction of plasma with magnetic field in the partially ionised solar atmosphere is frequently modelled via a single-fluid approximation, which is valid for the case of a strongly coupled collisional media, such as solar photosphere…

Solar and Stellar Astrophysics · Physics 2018-07-18 P. A. González-Morales , E. Khomenko , T. P. Downes , A. de Vicente

We extend recently-developed mesh-free Lagrangian methods for numerical magnetohydrodynamics (MHD) to arbitrary anisotropic diffusion equations, including: passive scalar diffusion, Spitzer-Braginskii conduction and viscosity, cosmic ray…

Instrumentation and Methods for Astrophysics · Physics 2017-07-11 Philip F. Hopkins