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In magnetized plasma, the magnetic field confines particles around field lines. The ratio between the intensity of the parallel and perpendicular viscosity or heat conduction may reach the order of $10^{12}$. When the magnetic fields have…

Numerical Analysis · Mathematics 2016-11-01 Yihong Wang , Wenjun Ying , Min Tang

When magnetohydrodynamic turbulence evolves in the presence of a large-scale mean magnetic field, an anisotropy develops relative to that preferred direction. The well-known tendency is to develop stronger gradients perpendicular to the…

Plasma Physics · Physics 2020-07-15 Rohit Chhiber , William H. Matthaeus , Sean Oughton , Tulasi N. Parashar

Steady state simulations} of magnetized electron fluid equations with strong anisotropic diffusion based on the first-order hyperbolic approach is carried out using cell-centered higher order upwind schemes, linear and weighted essentially…

Computational Physics · Physics 2019-03-14 Amareshwara Sainadh Chamarthi , Kimiya Komurasaki , Rei Kawashima

In the interstellar medium of galaxies and the intracluster gas of galaxy clusters, the charged particles making up cosmic rays are moving almost exclusively along (but not across) magnetic field lines. The resulting anisotropic transport…

Astrophysics of Galaxies · Physics 2016-08-31 Ruediger Pakmor , Christoph Pfrommer , Christine M. Simpson , Rahul Kannan , Volker Springel

We solve for waves in an isothermal, stratified medium with a magnetic field that points along a direction perpendicular to that of gravity and varies exponentially in the direction of gravity. We find exact analytical solutions for two…

Solar and Stellar Astrophysics · Physics 2022-06-17 B. Tripathi , Dhrubaditya Mitra

In this paper, we present a fast streamline-based numerical method for the two-phase flow equations in high-rate flooding scenarios for incompressible fluids in heterogeneous and anisotropic porous media. A fractional flow formulation is…

Numerical Analysis · Mathematics 2018-11-29 Ettore Vidotto , Martin Schneider , Rainer Helmig , Barbara Wohlmuth

Recent literature has effectively leveraged diffusion models trained on continuous variables as priors for solving inverse problems. Notably, discrete diffusion models with discrete latent codes have shown strong performance, particularly…

Computer Vision and Pattern Recognition · Computer Science 2025-09-22 Naoki Murata , Chieh-Hsin Lai , Yuhta Takida , Toshimitsu Uesaka , Bac Nguyen , Stefano Ermon , Yuki Mitsufuji

We investigate test-particle diffusion in dynamical turbulence based on a numerical approach presented before. For the turbulence we employ the nonlinear anisotropic dynamical turbulence model which takes into account wave propagation…

High Energy Astrophysical Phenomena · Physics 2016-09-28 Martin Heusen , Andreas Shalchi

A hybridized discontinuous Galerkin method is proposed for solving 2D fractional convection-diffusion equations containing derivatives of fractional order in space on a finite domain. The Riemann-Liouville derivative is used for the spatial…

Numerical Analysis · Mathematics 2016-07-12 Shuqin Wang , Jinyun Yuan , Weihua Deng , Yujiang Wu

This paper deals with an improvement of vertex based nonlinear diffusion for mesh denoising. This method directly filters the position of the vertices using Laplace, reduced centered Gaussian and Rayleigh probability density functions as…

Computer Vision and Pattern Recognition · Computer Science 2010-09-24 Mohammed EL Hassouni , Driss Aboutajdine

This article studies a direct numerical approach for fractional advection-diffusion equations (ADEs). Using a set of cubic trigonometric B-splines as test functions, a differential quadrature (DQ) method is firstly proposed for the 1D and…

Numerical Analysis · Mathematics 2017-10-19 X. G. Zhu , Y. F. Nie , W. W. Zhang

Preservation of the maximum principle is studied for the combination of the linear finite element method in space and the $\theta$-method in time for solving time dependent anisotropic diffusion problems. It is shown that the numerical…

Numerical Analysis · Mathematics 2013-10-23 Xianping Li , Weizhang Huang

Tracer tests in natural porous media sometimes show abnormalities that suggest considering a fractional variant of the Advection Diffusion Equation supplemented by a time derivative of non-integer order. We are describing an inverse method…

Classical Physics · Physics 2017-06-30 Boris Maryshev , Alain Cartalade , Christelle Latrille , Marie-Christine Néel

We theoretically analyze diffusion trajectories of an anisotropic object moving on a two dimensional space in the absence of an external field. In determining diffusion parameters associated with the shape anisotropy, we devise a measure…

Statistical Mechanics · Physics 2015-08-31 Sunghan Roh , Juyeon Yi , Yong Woon Kim

This paper proposes to address the issue of complexity reduction for the numerical simulation of multiscale media in a quasi-periodic setting. We consider a stationary elliptic diffusion equation defined on a domain $D$ such that…

Numerical Analysis · Mathematics 2019-09-11 Quentin Ayoul-Guilmard , Anthony Nouy , Christophe Binetruy

We study the effect of the non-linear process of ambipolar diffusion (joint transport of magnetic flux and charged particles relative to neutral particles) on the long-term behavior of a non-uniform magnetic field in a one-dimensional…

Solar and Stellar Astrophysics · Physics 2015-05-18 Jaime Hoyos , Andreas Reisenegger , Juan Valdivia

We generalize classical dispersion theory for a passive scalar to derive an asymptotic long-time convection-diffusion equation for a solute suspended in a wide, structured channel and subject to a steady low-Reynolds-number shear flow. Our…

Fluid Dynamics · Physics 2023-05-03 James V. Roggeveen , Howard A. Stone , Christina Kurzthaler

We discuss steady-state transonic outflows obtained by direct numerical solution of the hydrodynamic and magnetohydrodynamic equations. We make use of the Versatile Advection Code, a software package for solving systems of (hyperbolic)…

Astrophysics · Physics 2007-05-23 R. Keppens , J. P. Goedbloed

We derive the vorticity equation for an incompressible fluid on a 2-dimensional surface with arbitrary topology embedded in 3-dimensional Euclidean space by using a tailored Clebsch parametrization of the flow. In the inviscid limit, we…

Mathematical Physics · Physics 2022-09-21 Naoki Sato , Michio Yamada

We present a variationally separable splitting technique for the generalized-$\alpha$ method for solving parabolic partial differential equations. We develop a technique for a tensor-product mesh which results in a solver with a linear cost…

Numerical Analysis · Mathematics 2018-11-26 Pouria Behnoudfar , Victor M. Calo , Quanling Deng , Peter D. Minev
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