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This paper is concerned with moving mesh finite difference solution of partial differential equations. It is known that mesh movement introduces an extra convection term and its numerical treatment has a significant impact on the stability…

Numerical Analysis · Mathematics 2015-07-31 Weizhang Huang

This paper solves the two-dimensional Dirichlet problem for the Monge-Amp\`ere equation by a strong meshless collocation technique that uses a polynomial trial space and collocation in the domain and on the boundary. Convergence rates may…

Numerical Analysis · Mathematics 2017-12-27 Klaus Böhmer , Robert Schaback

We study in this work an integral formulation for the radiative transfer equation (RTE) in anisotropic media with truncated approximation to the scattering phase function. The integral formulation consists of a coupled system of integral…

Numerical Analysis · Mathematics 2019-08-29 Kui Ren , Hongkai Zhao , Yimin Zhong

Many naturally-occuring models in the sciences are well-approximated by simplified models, using multiscale techniques. In such settings it is natural to ask about the relationship between inverse problems defined by the original problem…

Numerical Analysis · Mathematics 2019-02-28 Kit Newton , Qin Li , Andrew Stuart

Since the early 1970s, inversion techniques have become the most useful tool for inferring the magnetic, dynamic, and thermodynamic properties of the solar atmosphere. The intrinsic model dependence makes it necessary to formulate specific…

Solar and Stellar Astrophysics · Physics 2016-12-07 Jose Carlos del Toro Iniesta , Basilio Ruiz Cobo

Recently, meshless methods have become popular in numerically solving partial differential equations and have been employed to solve equations governing fluid flows, heat transfer, and species transport. In the present study, a numerical…

Fluid Dynamics · Physics 2024-04-18 Akash Unnikrishnan , Vinod Narayanan , Surya Pratap Vanka

The homogenization procedure developed here is conducted on a laminate with periodic space-time modulation on the fine scale: at leading order, this modulation creates convection in the low-wavelength regime if both parameters are…

Analysis of PDEs · Mathematics 2024-07-12 Marie Touboul , Bruno Lombard , Raphaël Assier , Sébastien Guenneau , Richard Craster

Astrophysical plasmas are subject to a tight connection between magnetic fields and the diffusion of particles, which leads to an anisotropic transport of energy. Under the fluid assumption, this effect can be reduced to an…

Astrophysics of Galaxies · Physics 2016-01-13 Yohan Dubois , Benoît Commerçon

A new formalism is introduced for the transfer of polarized radiation. Stokes parameters are shown to be four-vectors in a Minkowski-like space and, most strikingly, the radiative transfer equation (RTE) turns out to be an infinitesimal…

Astrophysics · Physics 2007-05-23 A. Lopez Ariste , M. Semel

We propose a novel numerical approach for nonlocal diffusion equations [8] with integrable kernels, based on the relationship between the backward Kolmogorov equation and backward stochastic differential equations (BSDEs) driven by L\`{e}vy…

Numerical Analysis · Mathematics 2015-07-28 Guannan Zhang , Weidong Zhao , Clayton Webster , Max Gunzburger

Radiative transfer is a key component in almost all astrophysical and cosmological simulations. We present Magritte: a modern open-source software library for 3D radiative transfer. It uses a deterministic ray-tracer and formal solver, i.e.…

Instrumentation and Methods for Astrophysics · Physics 2020-01-08 Frederik De Ceuster , Ward Homan , Jeremy Yates , Leen Decin , Peter Boyle , James Hetherington

Radiation is an important contributor to the energetics of the interstellar medium, yet its transport is difficult to solve numerically. We present a novel approach towards solving radiative transfer of diffuse sources via backwards ray…

Instrumentation and Methods for Astrophysics · Physics 2023-02-15 A. Klepitko , S. Walch , R. Wünsch , D. Seifried , F. Dinnbier , S. Haid

Two-frequency radiative transfer (2f-RT) theory is developed for classical waves in random media. Depending on the ratio of the wavelength to the scale of medium fluctuation 2f-RT equation is either a Boltzmann-like integral equation with a…

Optics · Physics 2009-11-13 Albert C. Fannjiang

Solving the continuum radiative transfer equation in high opacity media requires sophisticated numerical tools. In order to test the reliability of such tools, we present a benchmark of radiative transfer codes in a 2D disc configuration.…

Solar and Stellar Astrophysics · Physics 2015-05-13 C. Pinte , T. J. Harries , M. Min , A. M. Watson , C. P. Dullemond , P. Woitke , F. Menard , M. C. Duran-Rojas

We study the standard spectral line radiative transfer equation for media consisting of resonant atoms and non-resonant components (the dust grains and the atoms without considered spectral transition). Our goal is to study the intensity…

Astrophysics of Galaxies · Physics 2017-06-21 N. A. Silant'ev , G. A. Alekseeva , V. V. Novikov

We proposed in a previous paper [Opt. Commun. 228, 33 (2003)] a modified radiative transfer equation to describe radiative transfer in a medium with a spatially varying refractive index. The present paper is devoted to the demonstration…

Optics · Physics 2008-05-23 Jean-Michel Tualle

We consider the inverse problem of reconstructing the optical parameters for stationary radiative transfer equation (RTE) from velocity-averaged measurement. The RTE often contains multiple scales characterized by the magnitude of a…

Numerical Analysis · Mathematics 2018-02-14 Ke Chen , Qin Li , Li Wang

We introduce a novel explicit and stable numerical algorithm to solve the spatially discretized heat or diffusion equation. We compare the performance of the new method with analytical and numerical solutions. We show that the method is…

Computational Physics · Physics 2020-08-04 Endre Kovács

Radiative transfer simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time their computational cost has come to the…

New high-resolution spectropolarimetric observations of solar prominences require improved radiative modelling capabilities in order to take into account both multi-dimensional - at least 2D - geometry and complex atomic models. This makes…

Astrophysics · Physics 2009-11-13 L. Leger , L. Chevallier , F. Paletou