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We describe the structure and implementation of a radiation hydrodynamic solver for MANGA, the moving-mesh hydrodynamics module of the large-scale parallel code, Charm N-body GrAvity solver (ChaNGa). We solve the equations of time dependent…

Instrumentation and Methods for Astrophysics · Physics 2020-03-04 Philip Chang , Shane W. Davis , Yan-Fei Jiang

A model for ionic and electronic grain boundary transport through thin films, scales or membranes with columnar grain structure is introduced. The grain structure is idealized as a lattice of identical hexagonal cells - a honeycomb pattern.…

Materials Science · Physics 2017-05-05 M. P. Tautschnig , N. M. Harrison , M. W. Finnis

In this paper, we study the non-linear diffusion equation associated with a particle system where the common drift depends on the rate of absorption of particles at a boundary. We provide an interpretation as a structural credit risk model…

Numerical Analysis · Mathematics 2018-08-28 Alexander Lipton , Vadim Kaushansky , Christoph Reisinger

Motivated by simulations of ultrasound-enhanced drug delivery, this work presents the numerical analysis of a mathematical model that captures the influence of ultrasound waves on the diffusivity of the drug. The system under study consists…

Numerical Analysis · Mathematics 2026-03-10 Femke de Wit , Vanja Nikolić

A new Monte-Carlo algorithm for calculating time-dependent radiative-transfer under the assumption of LTE is presented. Unlike flux-limited diffusion the method is polychromatic, includes scattering, and is able to treat the optically thick…

Solar and Stellar Astrophysics · Physics 2015-05-28 Tim J. Harries

We explore the diffusion process in the non-Markovian spatio-temporal noise.%the escape rate problem in the non-Markovian spatio-temporal random noise. There is a non-trivial short memory regime, i.e., the Markovian limit characterized by a…

Statistical Mechanics · Physics 2009-11-13 Takaaki Monnai , Ayumu Sugita , Katsuhiro Nakamura

The transport equations for polarized radiation transfer in non-Riemannian, Weyl-Cartan type space-times are derived, with the effects of both torsion and non-metricity included. To obtain the basic propagation equations we use the tangent…

General Relativity and Quantum Cosmology · Physics 2009-11-11 K. S. Cheng , T. Harko , X. Y. Wang

Analytic solutions to the nonlinear radiation diffusion equation with an instantaneous point source for a non-homogeneous medium with a power law spatial density profile, are presented. The solutions are a generalization of the well known…

Fluid Dynamics · Physics 2021-06-02 Menahem Krief

This contribution deals with the modeling of collisional multicomponent magnetized plasmas in thermal and chemical nonequilibrium aiming at simulating and predicting magnetic reconnections in the chromosphere of the sun. We focus on the…

Numerical Analysis · Mathematics 2021-06-01 Quentin Wargnier , Sylvain Faure , Benjamin Graille , Thierry Magin , Marc Massot

We consider nonlinear drift-diffusion equations (both porous medium equations and fast diffusion equations) with a measure-valued external force. We establish existence of nonnegative weak solutions satisfying gradient estimates, provided…

Analysis of PDEs · Mathematics 2025-01-15 Sukjung Hwang , Kyungkeun Kang , Hwa Kil Kim , Jung-Tae Park

We describe a general radiative equilibrium and temperature correction procedure for use in Monte Carlo radiation transfer codes with sources of temperature-independent opacity, such as astrophysical dust. The technique utilizes the fact…

Astrophysics · Physics 2010-04-08 J. E. Bjorkman , Kenneth Wood

The method of approximate automodel solution for the Green's function of the time-dependent superdiffusive (nonlocal) transport equations (J. Phys. A: Math. Theor. 49 (2016) 255002) is extended to the case of a finite velocity of carriers.…

Statistical Mechanics · Physics 2019-09-04 A. B. Kukushkin , A. A. Kulichenko

The response of a model micro-electrochemical system to a time-dependent applied voltage is analyzed. The article begins with a fresh historical review including electrochemistry, colloidal science, and microfluidics. The model problem…

Soft Condensed Matter · Physics 2009-11-10 Martin Z. Bazant , Katsuyo Thornton , Armand Ajdari

Aims. Numerical test-particle simulations are a reliable and frequently used tool to test analytical transport theories and to predict mean-free paths. The comparison between solutions of the diffusion equation and the particle flux is used…

High Energy Astrophysical Phenomena · Physics 2016-02-17 R. C. Tautz , J. Bolte , A. Shalchi

Context. Supernova remnants are known as sources of galactic cosmic rays for their non-thermal emission of radio waves, X-rays, and gamma-rays. However, the observed soft broken power-law spectra are hard to reproduce within standard…

High Energy Astrophysical Phenomena · Physics 2016-08-31 Robert Brose , Igor Telezhinsky , Martin Pohl

Numerical transfer matrices have been widely used in the study of wave propagation and scattering. These may be viewed as descretizations of a recently introduced fundamental notion of transfer matrix which admits a representation in terms…

Classical Physics · Physics 2023-10-03 Farhang Loran , Ali Mostafazadeh

In this paper, we study the existence of traveling wave solutions and the spreading speed for the solutions of an age-structured epidemic model with nonlocal diffusion. Our proofs make use of the comparison principles both to construct…

Analysis of PDEs · Mathematics 2024-05-24 Arnaud Ducrot , Hao Kang

A numerical scheme is proposed for the solution of the three-dimensional radiative transfer equation with variable optical depth. We show that time-dependent ray tracing is an attractive choice for simulations of astrophysical ionization…

Astrophysics · Physics 2009-10-31 Alexei Razoumov , Douglas Scott

The manuscript considers the model for conversion of mechanical energy into heat during acoustic wave propagation in the presence of temperature-dependent elastic parameters, as given by \[ \left\{ \begin{array}{l} u_{tt} = (\gamma(\Theta)…

Analysis of PDEs · Mathematics 2026-02-05 Felix Meyer , Michael Winkler

We present an analytical theory of thermonuclear X-ray burst atmosphere structure. Newtonian gravity and diffusion approximation are assumed. Hydrodynamic and thermodynamic profiles are obtained as a numerical solution of the Cauchy problem…

Astrophysics · Physics 2009-11-07 Nickolai Shaposhnikov , Lev Titarchuk