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A stochastic method is described for estimating Green's functions (GF's), appropriate to linear advection-diffusion-reaction transport problems, evolving in arbitrary geometries. By allowing straightforward construction of approximate,…

We present a novel numerical implementation of radiative transfer in the cosmological smoothed particle hydrodynamics (SPH) simulation code {\small GADGET}. It is based on a fast, robust and photon-conserving integration scheme where the…

Astrophysics · Physics 2009-06-23 M. Petkova , V. Springel

Transport and scattering phenomena in open quantum-systems with a continuous energy spectrum are conveniently solved using the time-dependent Schrodinger equation. In the time-dependent picture, the evolution of an initially localized…

Quantum Physics · Physics 2011-05-13 Tobias Kramer

In this paper, we consider the initial boundary value problem of the two dimensional multi-term time fractional mixed diffusion and diffusion-wave equations. An alternating direction implicit (ADI) spectral method is developed based on…

Numerical Analysis · Mathematics 2018-09-03 Zeting Liu , Fawang Liu , Fanhai Zeng

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

This paper builds on recent developments of adaptive methods for linear transport equations based on certain stable variational formulations of Petrov-Galerkin type. The variational formulations allow us to employ meshes with cells of…

Numerical Analysis · Mathematics 2016-01-05 W. Dahmen , G. Kutyniok , W. -Q Lim , C. Schwab , G. Welper

In this paper, we extend the operator-split asymptotic-preserving, semi-Lagrangian algorithm for time dependent anisotropic heat transport equation proposed in [Chac\'on et al., JCP, 272, 719-746, 2014] to use a fully implicit time…

Plasma Physics · Physics 2024-04-16 O. Koshkarov , L. Chacon

To describe the energy transport in the seismic coda, we introduce a system of radiative transfer equations for coupled surface and body waves in a scalar approximation. Our model is based on the Helmholtz equation in a half-space geometry…

Geophysics · Physics 2019-09-04 Ludovic Margerin , Andres Bajaras , Michel Campillo

We present a comprehensive analytical study of radiative transfer using the method of moments and include the effects of non-isotropic scattering in the coherent limit. Within this unified formalism, we derive the governing equations and…

Earth and Planetary Astrophysics · Physics 2015-06-19 Kevin Heng , João M. Mendonça , Jae-Min Lee

This paper discusses the spectral collocation method for numerically solving nonlocal problems: one dimensional space fractional advection-diffusion equation; and two dimensional linear/nonlinear space fractional advection-diffusion…

Numerical Analysis · Mathematics 2014-01-30 WenYi Tian , Weihua Deng , Yujiang Wu

We derive the radiative transfer equation for arbitrary stationary relativistic flows in stationary spacetimes, i.e. for steady-state transfer problems. We show how the standard characteristics method of solution developed by Mihalas and…

Astrophysics · Physics 2009-11-11 B. Chen , R. Kantowski , E. Baron , S. Knop , P. H. Hauschildt

This work demonstrates algorithms to accurately compute solutions to thermal radiation transport problems using a reduced floating-point precision implementation of the Implicit Monte Carlo method. Several techniques falling into the…

Computational Physics · Physics 2025-10-27 Simon Butson , Mathew Cleveland , Alex Long , Todd Palmer

Planning a safe and feasible trajectory for autonomous vehicles in real-time by fully utilizing perceptual information in complex urban environments is challenging. In this paper, we propose a spatio-temporal trajectory planning method…

Robotics · Computer Science 2025-02-26 Shan He , Yalong Ma , Tao Song , Yongzhi Jiang , Xinkai Wu

We derive a grey linear diffusion equation for photons with respect to inertial (or lab-frame) space and time, using asymptotic analysis in 1D planar geometry. The solution of the equation is the comoving radiation energy density. Our…

High Energy Astrophysical Phenomena · Physics 2026-02-12 Ryan T. Wollaeger , Jim E. Morel , Kendra P. Long , Mathew A. Cleveland , Robert B. Lowrie

The efficient numerical solution of Non-LTE multilevel transfer problems requires the combination of highly convergent iterative schemes with fast and accurate formal solution methods of the radiative transfer (RT) equation. This…

Astrophysics · Physics 2007-10-30 P. Fabiani Bendicho , J. Trujillo Bueno

Direct numerical simulation of diffusion through heterogeneous media can be difficult due to the computational cost of resolving fine-scale heterogeneities. One method to overcome this difficulty is to homogenize the model by replacing the…

Numerical Analysis · Mathematics 2020-11-24 Nathan G. March , Elliot J. Carr , Ian W. Turner

This work concerns the modeling of radiative transfer in anisotropic turbid media using diffusion theory. A theory for the relationship between microscopic scattering properties (i.e., an arbitrary differential scattering cross-section) and…

Optics · Physics 2014-08-14 Erik Alerstam

The quantum transport formalism based on tight-binding models is known to be powerful in dealing with a wide range of open physical systems subject to external driving forces but is, at the same time, limited by the memory requirement's…

Mesoscale and Nanoscale Physics · Physics 2012-10-01 Ming-Hao Liu , Klaus Richter

We propose a method of simulation that is based on the averaging of formal solutions of the transfer equation by taking the integral by the Monte Carlo method. This method is used to compute two models, which correspond to the limiting…

Astrophysics · Physics 2007-05-23 Maxim A. Voronkov

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