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We present the implementation of an implicit-explicit (IMEX) Runge-Kutta numerical scheme for general relativistic hydrodynamics coupled to an optically thick radiation field in two existing GR-hydrodynamics codes. We argue that the…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Constanze Roedig , Olindo Zanotti , Daniela Alic

The description of electronic exchange--correlation effects is of paramount importance for many applications in physics, chemistry, and beyond. In a recent Letter, Dornheim \textit{et al.} [\textit{Phys. Rev. Lett.}~\textbf{125}, 235001…

Plasma Physics · Physics 2021-04-07 Tobias Dornheim , Zhandos A. Moldabekov , Panagiotis Tolias

Estimation of Distribution Algorithms (EDAs) and Innovation Method are recognized methods for solving global optimization problems and for the estimation of parameters in diffusion processes, respectively. Well known is also that the…

Numerical Analysis · Mathematics 2018-04-10 Zochil González Arenas , Juan Carlos Jimenez , Li-Vang Lozada-Chang , Roberto Santana

This paper presents a new code for performing multidimensional radiation hydrodynamic (RHD) simulations on parallel computers involving anisotropic radiation fields and nonequilibrium effects. The radiation evolution modules described here…

Astrophysics · Physics 2009-11-07 John C. Hayes , Michael L. Norman

The electron energy distribution function (EEDF) in low-temperature plasmas exhibits features not fully captured by classical collisional models, particularly across the transition from kinetic to hydrodynamic regimes. This work attributes…

Plasma Physics · Physics 2025-07-16 Joel Saucedo , Uday Lamba , Hasitha Mahabaduge

Reduced fluid models including electron inertia and ion finite Larmor radius corrections are derived asymptotically, both from fluid basic equations and from a gyrofluid model. They apply to collisionless plasmas with small ion-to-electron…

Plasma Physics · Physics 2022-02-02 Thierry Passot , Pierre-Louis Sulem , Emanuele Tassi

Edge-enhancing diffusion (EED) can reconstruct a close approximation of an original image from a small subset of its pixels. This makes it an attractive foundation for PDE based image compression. In this work, we generalize second-order…

Computer Vision and Pattern Recognition · Computer Science 2020-06-19 Ikram Jumakulyyev , Thomas Schultz

In this paper we study the application of a simplified method to solve the dynamic radiative transfer problem in expanding envelopes. The method, which requires a computational effort similar to that of the diffusion approximation, is based…

Astrophysics · Physics 2009-10-28 J. Gomez-Gomar , J. Isern

Atmospheres having a significant radiative support are shown to be intrinsically unstable at luminosities above a critical fraction Gamma_crit ~ 0.5-0.85 of the Eddington limit, with the exact value depending on the boundary conditions. Two…

Astrophysics · Physics 2009-10-31 Nir J. Shaviv

Although EDM aims to unify the design space of diffusion models, its reliance on fixed Gaussian noise prevents it from explaining emerging flow-based methods that diffuse arbitrary noise. Moreover, our study reveals that EDM's forcible…

Computer Vision and Pattern Recognition · Computer Science 2026-03-06 Xingyu Qiu , Mengying Yang , Xinghua Ma , Dong Liang , Fanding Li , Gongning Luo , Wei Wang , Kuanquan Wang , Shuo Li

We employ Non-equilibrium Green's functions (NEGF) to describe the real-time dynamics of an adsorbate-surface model system exposed to ultrafast laser pulses. For a finite number of electronic orbitals, the system is solved exactly and…

Mesoscale and Nanoscale Physics · Physics 2016-05-04 E. Boström , M. Hopjan , A. Kartsev , C. Verdozzi , C. -O. Almbladh

This paper aims to establish a first general error estimate for numerical approximations of the system of reaction-diffusion equations (SRDEs), using reasonable regularity assumptions on the exact solutions. We employ the gradient…

Analysis of PDEs · Mathematics 2025-01-24 Yahya Alnashri

We consider the linear dissipative Boltzmann equation describing inelastic interactions of particles with a fixed background. For the simplified model of Maxwell molecules first, we give a complete spectral analysis, and deduce from it the…

Analysis of PDEs · Mathematics 2009-02-20 Bertrand Lods , Clément Mouhot , Giuseppe Toscani

In this paper a reaction-diffusion type equation is the starting point for setting up a genuine thermodynamic reduction, i.e. involving a finite number of parameters or collective variables, of the initial system. This program is carried…

Mathematical Physics · Physics 2016-11-17 Franco Cardin , Marco Favretti , Alberto Lovison

We deal with the electromagnetic waves propagation in the harmonic regime. We derive the Foldy-Lax approximation of the scattered fields generated by a cluster of small conductive inhomogeneities arbitrarily distributed in a bounded domain…

Analysis of PDEs · Mathematics 2018-02-12 Ali Bouzekri , Mourad Sini

Radiation hydrodynamics are a challenging multiscale and multiphysics set of equations. To capture the relevant physics of interest, one typically must time step on the hydrodynamics timescale, making explicit integration the obvious…

Numerical Analysis · Mathematics 2024-08-14 Ben S. Southworth , HyeongKae Park , Svetlana Tokareva , Marc Charest

Examination of equilibrium radiation in plasma media shows that the spectral the energy distribution of such radiation is different from the Planck equilibrium radiation. Using the previously obtained general relations for the spectral…

Statistical Mechanics · Physics 2019-09-04 Alexander M. Ignatov , Sergey A. Trigger

Diffusion is the macroscopic manifestation of disordered molecular motion. Mathematically, diffusion equations are partial differential equations describing the fluid-like large-scale dynamics of parcels of molecules. Spatially…

Fluid Dynamics · Physics 2018-10-26 F. Sattin , A. Bonato , L. Salasnich

We consider the numerical approximation of the radiative transfer equation using discontinuous angular and continuous spatial approximations for the even parts of the solution. The even-parity equations are solved using a diffusion…

Numerical Analysis · Mathematics 2019-09-19 Olena Palii , Matthias Schlottbom

In the article, new asymptotic approximation of the $n$th order is obtained and proposed to be used in calculations of radiation propagation without scattering in optically thick media; the asymptotic approximation is much simpler and more…

Instrumentation and Methods for Astrophysics · Physics 2020-12-23 S. A. Serov , S. S. Serova