An Explicit Scheme for Incorporating Ambipolar Diffusion in a Magnetohydrodynamics Code

Choi, Eunjin; Kim, Jong-Soo; Wiita, Paul J.

doi:10.1088/0067-0049/181/2/413

Cited by 41 publications

(58 citation statements)

References 41 publications

(48 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Then the friction force F fr can be taken roughly equal to the Lorentz force and replaced in the equation of motion of the neutrals, so that one eventually solves one set of MHD equations. Since it requires low ionization conditions, this method is suitable for ambipolar diffusion studies in molecular clouds (Shu et al 1987;Tóth 1994;Mac Low et al 1995;Choi et al 2009). …”

Section: Ambipolar Diffusion Implementationmentioning

confidence: 99%

The effect of ambipolar diffusion on low-density molecular ISM filaments

Ntormousi

Hennebelle

André

et al. 2016

A&A

View full text Add to dashboard Cite

Context. The filamentary structure of the molecular interstellar medium and the potential link of this morphology to star formation have been brought into focus recently by high resolution observational surveys. An especially puzzling matter is that local interstellar filaments appear to have the same thickness, independent of their column density. This requires a theoretical understanding of their formation process and the physics that governs their evolution. Aims. In this work we explore a scenario in which filaments are dissipative structures of the large-scale interstellar turbulence cascade and ion-neutral friction (also called ambipolar diffusion) is affecting their sizes by preventing small-scale compressions. Methods. We employ high-resolution (512 3 and 1024 3 ), 3D magnetohydrodynamic (MHD) simulations, performed with the grid code RAMSES, to investigate non-ideal MHD turbulence as a filament formation mechanism. We focus the analysis on the mass and thickness distributions of the resulting filamentary structures. Results. Simulations of both driven and decaying MHD turbulence show that the morphologies of the density and the magnetic field are different when ambipolar diffusion is included in the models. In particular, the densest structures are broader and more massive as an effect of ion-neutral friction and the power spectra of both the velocity and the density steepen at a smaller wavenumber. Conclusions. The comparison between ideal and non-ideal MHD simulations shows that ambipolar diffusion causes a shift of the filament thickness distribution towards higher values. However, none of the distributions exhibit the pronounced peak found in the observed local filaments. Limitations in dynamical range and the absence of self-gravity in these numerical experiments do not allow us to conclude at this time whether this is due to the different filament selection or due to the physics inherent of the filament formation.

show abstract

Section: Ambipolar Diffusion Implementationmentioning

confidence: 99%

The effect of ambipolar diffusion on low-density molecular ISM filaments

Ntormousi

Hennebelle

André

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…The super time stepping method is used to accelerate the timestep in high resolution calculations and/or in strong ambipolar diffusion. The test results of the decay of Alfvén waves in this paper and the steady-state oblique C-type shocks in Choi et al (2009) showed the accuracy and robustness of our numerical approach.…”

Section: Resultsmentioning

confidence: 60%

“…In addition to allowing larger effective time steps, the super time stepping approach offers relatively simple implementation. Readers who are interested in the technical details may look up Alexiades et al (1996) and Choi et al(2009). …”

Section: Ad Mhd Equations and Numerical Methodsmentioning

confidence: 99%

“…In fact, we also tested our code with this problem and presented its results in Figure 1 in Choi et al (2009). One drawback of this test problem is the steady-state nature, which doesn't enable us to check any states in between from an initial state to the final steady state.…”

Section: A New Test Problemmentioning

confidence: 99%

“…The successful simulation results show the flexibility of our method as well as its ability to follow complex MHD flows in the presence of ambipolar diffusion. Readers who are interested in these results may look up Choi et al (2009).…”

Section: A New Test Problemmentioning

confidence: 99%

See 2 more Smart Citations

A Fast Explicit Scheme for Solving MHD Equations with Ambipolar Diffusion

Kim

2010

Proc. IAU

Self Cite

View full text Add to dashboard Cite

Abstract. We developed a fast numerical scheme for solving ambipolar diffusion MHD equations with the strong coupling approximation, which can be written as the ideal MHD equations with an additional ambipolar diffusion term in the induction equation. The mass, momentum, magnetic fluxes due to the ideal MHD equations can be easily calculated by any Godunovtype schemes. Additional magnetic fluxes due to the ambipolar diffusion term are added in the magnetic fluxes, because of two same spatial gradients operated on the advection fluxes and the ambipolar diffusion term. In this way, we easily kept divergence-free magnetic fields using the constraint transport scheme. In order to overcome a small time step imposed by ambipolar diffusion, we used the super time stepping method. The resultant scheme is fast and robust enough to do the long term evolution of star formation simulations. We also proposed that the decay of alfven by ambipolar diffusion be a good test problem for our codes.

show abstract

Thermal instability in ionized plasma

Shadmehri

Nejad-Asghar

Khesali

2009

Astrophys Space Sci

View full text Add to dashboard Cite

We study magnetothermal instability in the ionized plasmas including the effects of Ohmic, ambipolar and Hall diffusion. Magnetic field in the single fluid approximation does not allow transverse thermal condensations, however, non-ideal effects highly diminish the stabilizing role of the magnetic field in thermally unstable plasmas. Therefore, enhanced growth rate of thermal condensation modes in the presence of the diffusion mechanisms speed up the rate of structure formation.

show abstract

An Explicit Scheme for Incorporating Ambipolar Diffusion in a Magnetohydrodynamics Code

Cited by 41 publications

References 41 publications

The effect of ambipolar diffusion on low-density molecular ISM filaments

The effect of ambipolar diffusion on low-density molecular ISM filaments

A Fast Explicit Scheme for Solving MHD Equations with Ambipolar Diffusion

Thermal instability in ionized plasma

Contact Info

Product

Resources

About