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Ambipolar diffusion is a process occurring in partially ionised astrophysical systems that imparts a complicated mathematical and physical nature to Ohm's law. The numerical codes that solve the magnetohydrodynamic (MHD) equations have to…

Solar and Stellar Astrophysics · Physics 2022-06-15 F. Moreno-Insertis , D. Nóbrega-Siverio , E. R. Priest , A. W. Hood

Astrophysical fluids under the influence of magnetic fields are often subjected to single-fluid or two-fluid approximations. In the case of weakly ionized plasmas however, this can be inappropriate due to distinct responses from the…

Astrophysics · Physics 2008-11-26 S. O'Sullivan , T. P. Downes

Astrophysical plasmas are subject to a tight connection between magnetic fields and the diffusion of particles, which leads to an anisotropic transport of energy. Under the fluid assumption, this effect can be reduced to an…

Astrophysics of Galaxies · Physics 2016-01-13 Yohan Dubois , Benoît Commerçon

Most numerical investigations on the role of magnetic fields in turbulent molecular clouds (MCs) are based on ideal magneto-hydrodynamics (MHD). However, MCs are weakly ionized, so that the time scale required for the magnetic field to…

Astrophysics · Physics 2009-11-13 Pak Shing Li , Christopher F. McKee , Richard I. Klein , Robert T. Fisher

We numerically model evolution of magnetic fields inside a neutron star under the influence of ambipolar diffusion in the weak-coupling mode in the one-fluid MHD approximation. Our simulations are three-dimensional and performed in…

High Energy Astrophysical Phenomena · Physics 2022-11-09 Andrei P. Igoshev , Rainer Hollerbach

In this work, we introduce the novel application of the adaptive mesh refinement (AMR) technique in the global stability analysis of incompressible flows. The design of an accurate mesh for transitional flows is crucial. Indeed, an…

Numerical Analysis · Mathematics 2026-02-17 Daniele Massaro , Valerio Lupi , Adam Peplinski , Philipp Schlatter

We have used the AMR hydrodynamic code, MG, to perform 3D magnetohydrodynamic simulations with self-gravity of stellar feedback in a sheet-like molecular cloud formed through the action of the thermal instability. We simulate the…

Astrophysics of Galaxies · Physics 2017-01-25 C. J. Wareing , J. M. Pittard , S. A. E. G. Falle

We performed a series of three-dimensional numerical simulations of supersonic homogeneous Euler turbulence with adaptive mesh refinement (AMR) and effective grid resolution up to 1024^3 zones. Our experiments describe non-magnetized driven…

Astrophysics · Physics 2016-08-30 Alexei G. Kritsuk , Michael L. Norman , Paolo Padoan

The formation of current sheets in ideal incompressible magnetohydrodynamic flows in two dimensions is studied numerically using the technique of adaptive mesh refinement. The growth of current density is in agreement with simple scaling…

comp-gas · Physics 2009-10-28 Holger Friedel , Rainer Grauer , Christiane Marliani

Observations indicate that dense molecular filamentary clouds are sites of star formation. The filament width determines the most unstable scale for self-gravitational fragmentation and influences the stellar mass. Therefore, constraining…

Astrophysics of Galaxies · Physics 2025-05-09 Daisei Abe , Tsuyoshi Inoue , Shu-ichiro Inutsuka , Doris Arzoumanian

We investigate the role of ambipolar diffusion (AD) in collisions between magnetized giant molecular clouds (GMCs), which may be an important mechanism for triggering star cluster formation. Three dimensional simulations of GMC collisions…

Astrophysics of Galaxies · Physics 2017-10-18 Duncan Christie , Benjamin Wu , Jonathan C. Tan

This paper describes the first steps of development of a new multidimensional time implicit code devoted to the study of hydrodynamical processes in stellar interiors. The code solves the hydrodynamical equations in spherical geometry and…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 M. Viallet , I. Baraffe , R. Walder

We introduce a new method to mitigate numerical diffusion in adaptive mesh refinement (AMR) simulations of cosmological galaxy formation, and study its impact on a simulated dwarf galaxy as part of the 'EDGE' project. The target galaxy has…

We study the buoyant rise of magnetic flux tubes embedded in an adiabatic stratification using two-and three-dimensional, MHD simulations. We analyze the dependence of the tube evolution on the field line twist and on the curvature of the…

Solar and Stellar Astrophysics · Physics 2015-11-18 Juan Martinez-Sykora , Fernando Moreno-Insertis , Mark C. M. Cheung

We simulate the early stages of the evolution of turbulent, virialized, high-mass protostellar cores, with primary attention to how cores fragment, and whether they form a small or large number of protostars. Our simulations use the Orion…

Astrophysics · Physics 2008-11-26 Mark R. Krumholz , Richard I. Klein , Christopher F. McKee

The photoionization-driven evaporation of planetary atmospheres has emerged as a potentially fundamental process for planets on short period orbits. While 1-D studies have proven the effectiveness of stellar fluxes at altering the…

Earth and Planetary Astrophysics · Physics 2018-12-19 Alex Debrecht , Jonathan Carroll-Nellenback , Adam Frank , John McCann , Ruth Murray-Clay , Eric G. Blackman

We use 3D computer modelling to investigate the timescales and radiative output from maser flares generated by the impact of shock-waves on astronomical unit-scale clouds in interstellar and star-forming regions, and in circumstellar…

Astrophysics of Galaxies · Physics 2024-04-17 M. D. Gray , S. Etoka , B. Pimpanuwat , A. M. S. Richards

We have explored the evolution of gas distributions from cosmological simulations carried out using the RAMSES adaptive mesh refinement (AMR) code, to explore the effects of resolution on cosmological hydrodynamical simulations. It is vital…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-28 Owain N. Snaith , Changbom Park , Juhan Kim , Joakim Rosdahl

GAMER, a parallel Graphic-processing-unit-accelerated Adaptive-MEsh-Refinement hydrodynamic code, has been extended to support magnetohydrodynamics (MHD) with both the corner-transport-upwind (CTU) and MUSCL-Hancock schemes and the…

Computational Physics · Physics 2018-06-22 Ui-Han Zhang , Hsi-Yu Schive , Tzihong Chiueh

The formation of protostellar disks out of molecular cloud cores is still not fully understood. Under ideal MHD conditions, the removal of angular momentum from the disk progenitor by the typically embedded magnetic field may prevent the…

Astrophysics of Galaxies · Physics 2015-05-30 R. Santos-Lima , E. M. de Gouveia Dal Pino , A. Lazarian