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Related papers: Kinetic Scheme for Solving M1 Model of Radiative T…

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A new kinetic model is proposed where the equilibrium distribution with bounded support has a range of velocities about two average velocities in 1D. In 2D, the equilibrium distribution function has a range of velocities about four average…

Fluid Dynamics · Physics 2023-08-15 Shashi Shekhar Roy , S. V. Raghurama Rao

We present a new numerical scheme to solve the transfer of diffuse radiation on three-dimensional mesh grids which is efficient on processors with highly parallel architecture such as recently popular GPUs and CPUs with multi- and many-core…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Satoshi Tanaka , Kohji Yoshikawa , Takashi Okamoto , Kenji Hasegawa

We present new methods for radiative transfer on hierarchial grids. We develop a new method for calculating the scattered flux that employs the grid structure to speed up the computation. We describe a novel subiteration algorithm that can…

Instrumentation and Methods for Astrophysics · Physics 2015-06-05 T. Lunttila , M. Juvela

We developed a three-dimensional radiative transfer code for an ultra-relativistic background flow-field by using the Monte Carlo (MC) method in the context of gamma-ray burst (GRB) emission. For obtaining reliable simulation results in the…

High Energy Astrophysical Phenomena · Physics 2017-09-13 Ayako Ishii , Naofumi Ohnishi , Hiroki Nagakura , Hirotaka Ito , Shoichi Yamada

A framework of finite-velocity model based Boltzmann equation has been developed for convection-diffusion equations. These velocities are kept flexible and adjusted to control numerical diffusion. A flux difference splitting based kinetic…

Numerical Analysis · Mathematics 2024-10-01 S. V. Raghurama Rao , K. S. Shrinath , Ankit Ruhi , Veeredhi Vasudeva Rao

A numerical scheme is described for including radiation in multi-dimensional general-relativistic conservative fluid dynamics codes. In this method, a covariant form of the M1 closure scheme is used to close the radiation moments, and the…

High Energy Astrophysical Phenomena · Physics 2013-01-16 Aleksander Sadowski , Ramesh Narayan , Alexander Tchekhovskoy , Yucong Zhu

The effective mass approximation is analysed in a nonperturbative kinetic theory approach to strong field excitations in graphene [1,2]. This problem is highly actual for the investigation of quantum radiation from graphene [3], where the…

Mesoscale and Nanoscale Physics · Physics 2023-01-31 D. B. Blaschke , V. V. Dmitriev , N. T. Gevorgyan , B. Mahato , A. D. Panferov , S. A. Smolyansky , V. A. Tseryupa

We consider in this contribution a simplified idealized one-dimensional model in a nuclear core reactor coupling the diffusion equation on the neutron flux withthe enthalpy equation for the water which collects the heat produced by this…

Numerical Analysis · Mathematics 2025-03-11 Olivier Lafitte , François Dubois

Monte Carlo methods are state-of-the-art when it comes to dosimetric computations in radiotherapy. However, the execution time of these methods suffers in high-collisional regimes. We address this problem by introducing a kinetic-diffusion…

Quantitative Methods · Quantitative Biology 2025-08-22 Klaas Willems , Vince Maes , Zhirui Tang , Giovanni Samaey

A fully adaptive finite volume multiresolution scheme for one-dimensional strongly degenerate parabolic equations with discontinuous flux is presented. The numerical scheme is based on a finite volume discretization using the…

Numerical Analysis · Mathematics 2008-07-03 Raimund Bürger , Ricardo Ruiz Baier , Mauricio Sepúlveda , Kai Schneider

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

Radiative transfer in a relativistic plane-parallel flow, e.g., an accretion disk wind, is examined in the fully special relativistic treatment. Under the assumption of a constant flow speed, for the relativistically moving atmosphere we…

High Energy Astrophysical Phenomena · Physics 2015-05-13 J. Fukue

We present a problem-suited numerical method for a particularly challenging cancer invasion model. This model is a multiscale haptotaxis advection-reaction-diffusion system that describes the macroscopic dynamics of two types of cancer…

Numerical Analysis · Mathematics 2016-05-18 Niklas Kolbe , Maria Lukacova-Medvidova , Nikolaos Sfakianakis , Bettina Wiebe

We provide a systematic description of the steps necessary -- and of the potential pitfalls to be encountered -- when implementing a two-moment scheme within an Implicit-Explicit (IMEX) scheme to include radiative-transfer contributions in…

General Relativity and Quantum Cosmology · Physics 2020-05-20 Lukas R. Weih , Hector Olivares , Luciano Rezzolla

In recent years, kinetic equations have been used to model many social phenomena. A key feature of these models is that transition rate kernels involve Dirac delta functions, which capture sudden, discontinuous state changes. Here, we study…

Numerical Analysis · Mathematics 2025-12-12 Yassin Bahid , Eduardo Corona , Nancy Rodriguez

The theory of heat transfer by electromagnetic radiation is based on the radiative transfer equation (RTE) for the radiation intensity, or equivalently on the Boltzmann transport equation (BTE) for the photon distribution. We focus in this…

Statistical Mechanics · Physics 2010-09-17 Thomas Christen , Frank Kassubek , Rudolf Gati

We discuss the efficiency of Monte Carlo methods in solving continuum radiative transfer problems. The sampling of the radiation field and convergence of dust temperature calculations in the case of optically thick clouds are both studied.…

Astrophysics · Physics 2009-11-10 M. Juvela

This paper is devoted to deal with some mathematical and numerical aspects of the radiative integral transfer equations. First, the properties of the raidative integral operators are analyzed. Based on these results, the existence and…

Numerical Analysis · Mathematics 2017-09-15 Yaochuang Han

In plasma edge simulations, the behavior of neutral particles is often described by a Boltzmann--BGK equation. Solving this kinetic equation and estimating the moments of its solution are essential tasks, typically carried out using Monte…

Numerical Analysis · Mathematics 2025-12-30 Zhirui Tang , Julian Koellermeier , Emil Løvbak , Giovanni Samaey

We investigate numerically a model consisting in a kinetic equation for the biased motion of bacteria following a run-and-tumble process, coupled with two reaction-diffusion equations for chemical signals. This model exhibits asymptotic…

Analysis of PDEs · Mathematics 2018-11-26 Vincent Calvez , Laurent Gosse , Monika Twarogowska