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We consider a particle moving in $d\geq 2$ dimensions, its velocity being a reversible diffusion process, with identity diffusion coefficient, of which the invariant measure behaves, roughly, like $(1+|v|)^{-\beta}$ as $|v|\to \infty$, for…

Probability · Mathematics 2018-12-18 Nicolas Fournier , Camille Tardif

In this paper, we focus on the two-dimensional surface quasi-geostrophic equation with fractional horizontal dissipation and fractional vertical thermal diffusion. On the one hand, when the dissipation powers are restricted to a suitable…

Analysis of PDEs · Mathematics 2021-12-28 Zhuan Ye

At this time there does not exist a robust set of rules connecting low and high $\beta$ waves across the $\beta \approx 1$ layer. The work here contributes specifically to what happens when a low $\beta$ fast wave crosses the $\beta \approx…

Astrophysics · Physics 2008-11-26 J. A. McLaughlin , A. W. Hood

In this paper, we study small perturbations of a class of non-convex integrable Hamiltonians with two degrees of freedom, and we prove a result of diffusion for an open and dense set of perturbations, with an optimal time of diffusion which…

Dynamical Systems · Mathematics 2013-11-11 Abed Bounemoura , Vadim Kaloshin

Consideration in this paper is the global well-posedness for the 3D axisymmetric MHD equations with only vertical dissipation and vertical magnetic diffusion. The existence of unique low-regularity global solutions of the system with…

Analysis of PDEs · Mathematics 2023-10-11 Hammadi Abidi , Guilong Gui , Xueli Ke

We investigate the intermittency of energy dissipation in magnetohydrodynamic (MHD) turbulence by identifying dissipative structures and measuring their characteristic scales. We find that the probability distribution of energy dissipation…

Solar and Stellar Astrophysics · Physics 2014-10-28 Vladimir Zhdankin , Stanislav Boldyrev , Jean Carlos Perez , Steven M. Tobias

In this paper, we prove global existence of solutions with analytic regularity to the 2D MHD boundary layer equations in the mixed Prandtl and Hartmann regime derived by formal multi-scale expansion in \cite{GP}. The analysis shows that the…

Analysis of PDEs · Mathematics 2018-07-10 Feng Xie , Tong Yang

As a continuation of the previous work [40], in this paper we focus on the Cauchy problem of the two-dimensional (2D) incompressible Boussinesq equations with fractional Laplacian dissipation. We give an elementary proof of the global…

Analysis of PDEs · Mathematics 2016-01-27 Zhuan Ye , Xiaojing Xu

This paper presents both rigorous results and physical theory on the breakdown of magnetic flux conservation for ideal plasmas, by nonlinear effects. Our analysis is based upon an effective equation for magnetohydrodynamic (MHD) modes at…

Plasma Physics · Physics 2015-06-26 Gregory L. Eyink , Hussein Aluie

We prove non-uniqueness in law of the three-dimensional magnetohydrodynamics system that is forced by random noise of an additive and a linear multiplicative type and has viscous and magnetic diffusion, both of which are weaker than a full…

Analysis of PDEs · Mathematics 2021-09-16 Kazuo Yamazaki

We consider the stationary (time-independent) Navier-Stokes equations in the whole threedimensional space, under the action of a source term and with the fractional Laplacian operator (--$\Delta$) $\alpha$/2 in the diffusion term. In the…

Analysis of PDEs · Mathematics 2024-05-16 Oscar Jarrín , Gastón Vergara-Hermosilla

We have extended our previous mean-field galactic dynamo model which included algebraic and dynamic alpha nonlinearities (Kleeorin et al., A&A, v. 387, 453, 2002), to include also a quenching of turbulent diffusivity. We readily obtain…

Astrophysics · Physics 2014-10-13 N. Kleeorin , D. Moss , I. Rogachevskii , D. Sokoloff

We develop a new framework for the modelling of charged fluid dynamics in general relativity. The model, which builds on a recently developed variational multi-fluid model for dissipative fluids, accounts for relevant effects like the…

General Relativity and Quantum Cosmology · Physics 2017-05-31 N. Andersson , K. Dionysopoulou , I. Hawke , G. L. Comer

We consider a two-dimensional MHD model describing the evolution of viscous, compressible and electrically conducting fluids under the action of vertical magnetic field without resistivity. Existence of global weak solutions is established…

Analysis of PDEs · Mathematics 2019-07-02 Yang Li , Yongzhong Sun

A quantum mechanical model is used to derive a generalized Landau-Lifshitz equation for a magnetic moment, including fluctuations and dissipation. The model reproduces the Gilbert-Brown form of the equation in the classical limit. The…

Materials Science · Physics 2009-11-07 A. Rebei , G. J. Parker

This work investigates the existence and uniqueness of local weak solutions for the d-dimensional $(d \geq 2)$ fractional magnetic B\'enard system without thermal diffusion, integrating the B\'enard equation and MHD system. For $\kappa = 0$…

Analysis of PDEs · Mathematics 2024-09-27 Anis Rahmani , Abdelaziz Mennouni

This paper is concerned with the Cauchy problem of the two-dimensional MHD system with magnetic diffusion. It was proved that the MHD equations have a unique global strong solution around the equilibrium state $(0, e_1)$. Furthermore, the…

Analysis of PDEs · Mathematics 2020-09-10 Zhouyu Li , Pan Liu , Pengcheng Niu

The behavior of the self diffusion constant of Langevin particles interacting via a pairwise interaction is considered. The diffusion constant is calculated approximately within a perturbation theory in the potential strength about the bare…

Soft Condensed Matter · Physics 2009-11-10 D. S. Dean , A. Lefèvre

We study the regularity of segregated profiles arising from competition - diffusion models, where the diffusion process is of nonlocal type and is driven by the fractional Laplacian of power $s \in (0,1)$. Among others, our results apply to…

Analysis of PDEs · Mathematics 2019-05-14 Giorgio Tortone , Alessandro Zilio

We describe the crossover from generalized hydrodynamics to conventional hydrodynamics in nearly integrable systems. Integrable systems have infinitely many conserved quantities, which spread ballistically in general. When integrability is…

Statistical Mechanics · Physics 2020-05-13 Aaron J. Friedman , Sarang Gopalakrishnan , Romain Vasseur