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We study the validity of the time-dependent asymptotic $P_N$ approximation in radiative transfer of photons. The time-dependent asymptotic $P_N$ is an approximation which uses the standard $P_N$ equations with a closure that is based on the…

Computational Physics · Physics 2021-08-26 Re'em Harel , Stanislav Burov , Shay I. Heizler

In this paper we propose an asymptotic preserving scheme for a family of Friedrichs systems on unstructured meshes based on a decomposition between the hyperbolic heat equation and a linear hyperbolic which not involved in the di usive…

Numerical Analysis · Mathematics 2013-04-11 Christophe Buet , Bruno Després , Emmanuel Franck

Asymptotic preserving (AP) schemes are targeting to simulate both continuum and rarefied flows. Many AP schemes have been developed and are capable of capturing the Euler limit in the continuum regime. However, to get accurate Navier-Stokes…

Fluid Dynamics · Physics 2015-05-08 Songze Chen , Kun Xu

We present a numerical implementation of radiative transfer based on an explicitly photon-conserving advection scheme, where radiative fluxes over the cell interfaces of a structured or unstructured mesh are calculated with a second-order…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Margarita Petkova , Volker Springel

We present the asymptotic transitions from microscopic to macroscopic physics, their computational challenges and the Asymptotic-Preserving (AP) strategies to efficiently compute multiscale physical problems. Specifically, we will first…

Numerical Analysis · Mathematics 2021-12-14 Shi Jin

Discontinuous Galerkin (DG) methods are widely adopted to discretize the radiation transport equation (RTE) with diffusive scalings. One of the most important advantages of the DG methods for RTE is their asymptotic preserving (AP)…

Numerical Analysis · Mathematics 2024-04-17 Cory D. Hauck , Qiwei Sheng , Yulong Xing

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

We present an extension of TRAPHIC, the method for radiative transfer of ionising radiation in smoothed particle hydrodynamics simulations that we introduced in Pawlik & Schaye (2008). The new version keeps all advantages of the original…

Instrumentation and Methods for Astrophysics · Physics 2011-05-10 Andreas H. Pawlik , Joop Schaye

We develop novel asymptotic-preserving (AP) deterministic particle methods for collisional plasma models, including both Landau--Fokker--Planck and Dougherty collision operators, under hydrodynamic scaling. Our schemes treat the non-stiff…

Numerical Analysis · Mathematics 2026-04-13 Yan Huang , Li Wang

We consider a class of multiscale parabolic problems with diffusion coefficients oscillating in space at a possibly small scale $\varepsilon$. Numerical homogenization methods are popular for such problems, because they capture efficiently…

Numerical Analysis · Mathematics 2016-08-18 Nicolas Crouseilles , Mohammed Lemou , Gilles Vilmart

Although the Boltzmann transport equation (BTE) has been exploited to investigate non-diffusive phonon transport for decades, due to the challenges of solving this integro-differential equation, most standard techniques for thermal…

Materials Science · Physics 2024-08-13 Tao Li , Bo Jiang , Zhen Chen

We consider a parameter dependent family of damped hyperbolic equations with interesting limit behavior: the system approaches steady states exponentially fast and for parameter to zero the solutions converge to that of a parabolic limit…

Numerical Analysis · Mathematics 2017-04-19 Herbert Egger , Thomas Kugler

This paper presents nonlinear iterative methods for the fundamental thermal radiative transfer (TRT) model defined by the time-dependent multifrequency radiative transfer (RT) equation and the material energy balance (MEB) equation. The…

Numerical Analysis · Mathematics 2024-09-24 Dmitriy Y. Anistratov

The numerical approximation of high-dimensional evolution equations poses significant computational challenges, particularly in kinetic theory and radiative transfer. In this work, we introduce the Galerkin Alternating Projection (GAP)…

Numerical Analysis · Mathematics 2025-05-27 Gianluca Ceruti , Nicolas Crouseilles , Lukas Einkemmer

We present a scheme for achieving thermal bistability based on the selective coupling of three optical resonances. This approach requires one of the resonant frequencies to be temperature dependent, which can occur in materials exhibiting…

Mesoscale and Nanoscale Physics · Physics 2017-09-13 Chinmay Khandekar , Alejandro W. Rodriguez

We consider two distinguished asymptotic limits of the Euler equations in a gravitational field, namely the incompressible and Boussinesq limits. Both these limits can be obtained as singular limits of the Euler equations under appropriate…

Numerical Analysis · Mathematics 2019-02-04 K. R. Arun , S. Samantaray

In this paper, we derive two bound-preserving and mass-conserving schemes based on the fractional-step method and high-order compact (HOC) finite difference method for nonlinear convection-dominated diffusion equations. We split the…

Numerical Analysis · Mathematics 2024-09-16 Baolin Kuang , Hongfei Fu , Shusen Xie

An asymptotic preserving and energy stable scheme for the barotropic Euler system under the low Mach number scaling is designed and analysed. A velocity shift proportional to the pressure gradient is introduced in the convective fluxes,…

Numerical Analysis · Mathematics 2023-07-21 K. R. Arun , Rahuldev Ghorai , Mainak Kar

We introduce the radiative transfer postprocessing code Subsweep. The code is based on the method of transport sweeps, in which the exact solution to the scattering-less radiative transfer equation is computed in a single pass through the…

Instrumentation and Methods for Astrophysics · Physics 2024-12-03 Toni Peter , Joseph S. W. Lewis , Ralf S. Klessen , Simon C. O. Glover , Guido Kanschat

We develop a self-consistent theoretical formalism to model the dynamics of heat transfer in dissipative, dispersive, anisotropic nanoscale media, such as metamaterials. We employ our envelope dyadic Green's function method to solve…

Classical Physics · Physics 2024-11-19 Hodjat Mariji , Stanislav Maslovski