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Solving the null geodesic equations for a ray of light is a difficult task even considering a stationary spacetime. The problem becomes even more difficult if the electromagnetic signal propagates through a flowing optical medium. Indeed,…

General Relativity and Quantum Cosmology · Physics 2024-03-25 Adrien Bourgoin , Pierre Teyssandier , Paolo Tortora , Marco Zannoni

New mathematical and numerical results are given for the coupling of the temperature equation of a fluid with Radiative Transfer: existence and uniqueness and a convergent monotone numerical scheme. The technique is shown to be feasible for…

Numerical Analysis · Mathematics 2021-07-30 F. Golse , O. Pironneau

The development of radiation hydrodynamical methods that are able to follow gas dynamics and radiative transfer self-consistently is key to the solution of many problems in numerical astrophysics. Such fluid flows are highly complex, rarely…

Graphene has proven to host outstanding mesoscopic effects involving massless Dirac quasiparticles travelling ballistically resulting in the current flow exhibiting light-like behaviour. A new branch of 2D electronics inspired by the…

Mesoscale and Nanoscale Physics · Physics 2018-08-22 Gaetano Calogero , Nick R. Papior , Peter Bøggild , Mads Brandbyge

The thermal radiative transfer (TRT) equations form an integro-differential system that describes the propagation and collisional interactions of photons. Computing accurate and efficient numerical solutions TRT are challenging for several…

Numerical Analysis · Mathematics 2021-11-09 Ryan G. McClarren , James A. Rossmanith , Minwoo Shin

A dynamical method for inelastic transport simulations in nanostructures is compared with a steady-state method based on non-equilibrium Green's functions. A simplified form of the dynamical method produces, in the steady state in the…

Mesoscale and Nanoscale Physics · Physics 2008-08-19 Eunan J. McEniry , Thomas Frederiksen , Tchavdar N. Todorov , Daniel Dundas , Andrew P. Horsfield

Heat transfer between graphene and water is pivotal for various applications, including solarthermal vapor generation and the advanced manufacturing of graphene-based hierarchical structures in solution. In this study, we employ a…

Materials Science · Physics 2024-09-02 Haoran Cui , Iyyappa Rajan Panneerselvam , Pranay Chakraborty , Qiong Nian , Yiliang Liao , Yan Wang

In this paper we report on the improvements implemented in the cosmological radiative transfer code CRASH. In particular we present a new multi-frequency algorithm for spectra sampling which makes use of colored photon packets: we discuss…

Astrophysics · Physics 2009-11-13 A. Maselli , B. Ciardi , A. Kanekar , .

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 present a novel, easy-to-use method based on the photon-mapping technique to simulate photometric images of moving targets. Realistic images can be created in two passes: photon tracing and image rendering. The nature of light sources,…

Instrumentation and Methods for Astrophysics · Physics 2021-10-13 Junju Du , Shaoming Hu , Xu Chen , Hai Cao , Yuchen Jiang

To determine the electron heat flux density on macroscopic scales, the most widely used approach is to solve a diffusion equation through a multi-group technique. This method is however restricted to transport induced by temperature…

Thermal radiation transport is a challenging problem in computational physics that has long been approached primarily in one of a few standard ways: approximate moment methods (for instance P$_1$ or M$_1$), implicit Monte Carlo, discrete…

Instrumentation and Methods for Astrophysics · Physics 2026-02-04 J. C. Dolence , H. R. Hammer , H. Park , B. Prather , B. R. Ryan , R. T. Wollaeger

This work introduces progressive spatio-temporal filtering, an efficient method to build all-frequency approximations to the light transport distribution into a scene by filtering individual samples produced by an underlying path sampler,…

Graphics · Computer Science 2020-05-26 Jacopo Pantaleoni

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

In this work, we present an expression for the near-field thermal radiative transfer between two spheres with an arbitrary numbers of coatings. We numerically demonstrate that the spectrum of heat transfer between layered spheres exhibits…

Mesoscale and Nanoscale Physics · Physics 2017-09-13 Braden Czapla , Arvind Narayanaswamy

We describe a photon-conserving radiative transfer algorithm, using a spatially-adaptive ray tracing scheme, and its parallel implementation into the adaptive mesh refinement (AMR) cosmological hydrodynamics code, Enzo. By coupling the…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 John H. Wise , Tom Abel

Biomedical optical imaging has a possibility of a comprehensive diagnosis of thyroid cancer in conjunction with ultrasound imaging. For improvement of the optical imaging, this study develops a higher order scheme for solving the…

Medical Physics · Physics 2016-03-15 Hiroyuki Fujii , Shinpei Okawa , Ken Nadamoto , Eiji Okada , Yukio Yamada , Yoko Hoshi , Masao Watanabe

In this paper, we extend the unified kinetic particle (UGKP) method to the frequency-dependent radiative transfer equation with both absorption-emission and scattering processes. The extended UGKP method could not only capture the diffusion…

Computational Physics · Physics 2023-02-17 Yuan Hu , Chang Liu

We propose a new colour transfer method with Optimal Transport (OT) to transfer the colour of a sourceimage to match the colour of a target image of the same scene that may exhibit large motion changes betweenimages. By definition OT does…

Computer Vision and Pattern Recognition · Computer Science 2020-05-20 Hana Alghamdi , Rozenn Dahyot

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