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A density-functional theory is established for inhomogeneous superfluids at finite temperature, subject to time-dependent external fields in isothermal conditions. After outlining parallelisms between a neutral superfluid and a charged…

Statistical Mechanics · Physics 2009-10-31 M. L. Chiofalo , M. P. Tosi

Turbulence is essential for understanding the structure and dynamics of molecular clouds and star-forming regions. There is a need for adequate tools to describe and characterize the properties of turbulent flows. One-point probability…

Astrophysics · Physics 2008-11-26 Ralf S. Klessen

Initial results from simulations of 4-fluid MHD turbulence in molecular clouds are presented. The species included in the simulations are ions, electrons, negatively charged dust grains and neutrals. The results indicate that, on length…

Astrophysics of Galaxies · Physics 2012-08-02 Turlough P. Downes

It is shown that the Cauchy problem of the equations in magnetohydrodynamics in the whole space is globally well-posed for any initial smooth and localized data. In general, the mathematical structure of solution shows that the coupled…

Fluid Dynamics · Physics 2023-06-14 F. Lam

We present numerical simulations of electron magnetohydrodynamic (EMHD) and electron reduced MHD (ERMHD) turbulence. Comparing scaling relations, we find that both EMHD and ERMHD turbulence show similar spectra and anisotropy. We develop…

Earth and Planetary Astrophysics · Physics 2009-07-24 Jungyeon Cho , A. Lazarian

We introduce the concept of intermittency dimension for the magnetohydrodynamics (MHD) to quantify the intermittency effect. With dependence on the intermittency dimension, we derive phenomenological laws for intermittent MHD turbulence…

Analysis of PDEs · Mathematics 2020-12-22 Mimi Dai

In helical hydromagnetic turbulence with an imposed magnetic field (which is constant in space and time) the magnetic helicity of the field within a periodic domain is no longer an invariant of the ideal equations. Alternatively, there is a…

Astrophysics · Physics 2009-11-07 Axel Brandenburg , William H. Matthaeus

The two-fluid Maxwell system couples frictionless electron and ion fluids via Maxwell's equations. When the frequencies of light waves, Langmuir waves, and single-particle cyclotron motion are scaled to be asymptotically large, the…

Plasma Physics · Physics 2017-08-02 J. W. Burby

This paper concerns the rigorous periodic homogenization for a non-linear strongly coupled system, which models a suspension of magnetizable rigid particles in a non-conducting carrier viscous Newtonian fluid. The fluid drags the particles,…

Analysis of PDEs · Mathematics 2022-02-15 Thuyen Dang , Yuliya Gorb , Silvia Jiménez Bolaños

Observations in polarized emission reveal the existence of large-scale coherent magnetic fields in a wide range of spiral galaxies. Radio-polarization data show that these fields are strongly inclined towards the radial direction, with…

Astrophysics · Physics 2009-11-13 Oliver Gressel , Udo Ziegler , Detlef Elstner , Günther Rüdiger

We present an application of the theory of stochastic processes to model and categorize non-equilibrium physical phenomena. The concepts of uniformly continuous probability measures and modular evolution lead to a systematic hierarchical…

Mathematical Physics · Physics 2009-08-18 Enrique Hernandez-Lemus , Jesus K. Estrada-Gil

In paper I, we obtained an equation for the evolution of density inhomogeneities in a radiation dominated universe when they are affected by magnetic fields. In this second paper we apply this equation to the case in which the subjacent…

Astrophysics · Physics 2016-08-30 E. Florido , E. Battaner

This paper studies the nonlinear evolution of magnetic field turbulence in proximity of steady ideal MHD configurations characterized by a small electric current, a small plasma flow, and approximate flux surfaces, a physical setting that…

Plasma Physics · Physics 2024-09-12 Naoki Sato , Michio Yamada

This paper proposes and analyzes arbitrarily high-order discontinuous Galerkin (DG) and finite volume methods which provably preserve the positivity of density and pressure for the ideal MHD on general meshes. Unified auxiliary theories are…

Numerical Analysis · Mathematics 2020-05-05 Kailiang Wu , Chi-Wang Shu

We propose a result of global stability for the equations of homogeneous, incompressible magnetohydrodynamics (MHD) on a torus of any dimension $d \in \{2,3,...\}$, with positive viscosity and resistivity. This result applies to the…

Analysis of PDEs · Mathematics 2026-02-09 Livio Pizzocchero , Emanuele Tassi

The Generalized Hasegawa-Mima (GHM) equation, which generalizes the standard Hasegawa-Mima (HM) equation, is a nonlinear equation describing the evolution of drift wave turbulence in curved magnetic fields. The GHM equation can be obtained…

Plasma Physics · Physics 2024-01-02 Naoki Sato , Michio Yamada

Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. These configurations are described by time self-similar dynamics, where space and time dependences of…

Astrophysics · Physics 2012-10-18 K. H. Tsui

The Hosking integral, which characterizes magnetic helicity fluctuations in subvolumes, is known to govern the decay of magnetically dominated turbulence. Here we show that, when the evolution of the magnetic field is controlled by the…

Plasma Physics · Physics 2023-09-14 Axel Brandenburg

We use ensemble machine learning algorithms to study the evolution of magnetic fields in magnetohydrodynamic (MHD) turbulence that is helically forced. We perform direct numerical simulations of helically forced turbulence using mean field…

Solar and Stellar Astrophysics · Physics 2019-09-11 Farrukh Nauman , Joonas Nättilä

We consider the problem of incompressible, forced, nonhelical, homogeneous, isotropic MHD turbulence with no mean magnetic field. This problem is essentially different from the case with externally imposed uniform mean field. There is no…

Astrophysics · Physics 2008-11-26 A. A. Schekochihin , S. C. Cowley , S. F. Taylor , J. L. Maron , J. C. McWilliams