Ambipolar diffusion in smoothed particle magnetohydrodynamics

Abstract

In partially ionised plasmas, the magnetic field can become decoupled from the neutral gas and diffuse through it in a process known as ambipolar diffusion. Although ambipolar diffusion has been implemented in several grid codes, we here provide an implementation in smoothed particle magnetohydrodynamics (SPMHD). We use the strong coupling approximation in which the ion density is negligible, allowing a single fluid approach. The equations are derived to conserve energy, and to provide a positive definite contribution to the entropy. We test the implementation in both a simple 1D SPMHD code and the fully 3D code PHANTOM. The wave damping test yields agreement within 0.03-2 per cent of the analytical result, depending on the value of the collisional coupling constant. The oblique C-shocks test yields results that typically agree within 4 per cent of the semi-analytical result. Our algorithm is therefore suitable for exploring the effect ambipolar diffusion has on physical processes, such as the formation of stars from molecular clouds.

Accepted for publication by MNRAS

References in corpus (12)

• Athena: A New Code for Astrophysical MHD
• Smoothed Particle Hydrodynamics and Magnetohydrodynamics
• The impact of magnetic fields on single and binary star formation
• Magnetically Regulated Star Formation in 3D: The Case of Taurus Molecular Cloud Complex
• Hall magnetohydrodynamics of partially ionized plasmas
• The effect of magnetic fields on star cluster formation
• MAGMA: a 3D, Lagrangian magnetohydrodynamics code for merger applications
• Constrained Hyperbolic Divergence Cleaning for Smoothed Particle Magnetohydrodynamics
• Second Core Formation and High Speed Jets: Resistive MHD Nested Grid Simulations
• Three-fluid plasmas in star formation I. Magneto-hydrodynamic equations
• Simulating hydromagnetic processes in star formation: introducing ambipolar diffusion into an adaptive mesh refinement code
• An Explicit Scheme for Incorporating Ambipolar Diffusion in a Magnetohydrodynamics Code

Cited by in corpus (4)

• Effects of Ohmic and ambipolar diffusion on the formation and evolution of the first cores, protostars and circumstellar discs
• Constrained hyperbolic divergence cleaning in smoothed particle magnetohydrodynamics with variable cleaning speeds
• NICIL: A stand alone library to self-consistently calculate non-ideal magnetohydrodynamic coefficients in molecular cloud cores
• The impact of non-ideal magnetohydrodynamics on binary star formation