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We introduce a simple and efficient algorithm for diffusion in smoothed particle hydrodynamics (SPH) simulations and apply it to the problem of chemical mixing. Based on the concept of turbulent diffusion, we link the diffusivity of a…

Astrophysics · Physics 2009-11-13 Thomas H. Greif , Simon C. O. Glover , Volker Bromm , Ralf S. Klessen

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

Krylov subspace, which is generated by multiplying a given vector by the matrix of a linear transformation and its successive powers, has been extensively studied in classical optimization literature to design algorithms that converge…

Machine Learning · Computer Science 2024-02-20 Hyungjin Chung , Suhyeon Lee , Jong Chul Ye

A moving mesh finite difference method based on the moving mesh partial differential equation is proposed for the numerical solution of the 2T model for multi-material, non-equilibrium radiation diffusion equations. The model involves…

Numerical Analysis · Mathematics 2020-04-20 Xiaobo Yang , Weizhang Huang , Jianxian Qiu

Non-equilibrium radiation diffusion is an important mechanism of energy transport in Inertial Confinement Fusion, astrophysical plasmas, furnaces and heat exchangers. In this paper, an analytical solution to the non-equilibrium Marshak…

Mathematical Physics · Physics 2013-01-17 Karabi Ghosh

Radiative transfer has a strong impact on the collapse and the fragmentation of prestellar dense cores. We present the radiation-hydrodynamics solver we designed for the RAMSES code. The method is designed for astrophysical purposes, and in…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Benoit Commercon , Romain Teyssier , Edouard Audit , Patrick Hennebelle , Gilles Chabrier

When integrating the radiative transfer equation for polarized light, the necessity of high-order numerical methods is well known. In fact, well-performing high-order formal solvers enable higher accuracy and the use of coarser spatial…

Solar and Stellar Astrophysics · Physics 2017-09-06 Gioele Janett , Oskar Steiner , Luca Belluzzi

We have developed a three-dimensional radiative transfer method designed specifically for use with parallel adaptive mesh refinement hydrodynamics codes. This new algorithm, which we call hybrid characteristics, introduces a novel form of…

Astrophysics · Physics 2009-11-11 Erik-Jan Rijkhorst , Tomasz Plewa , Anshu Dubey , Garrelt Mellema

Diffusion-based image super-resolution (SR) methods are mainly limited by the low inference speed due to the requirements of hundreds or even thousands of sampling steps. Existing acceleration sampling techniques inevitably sacrifice…

Computer Vision and Pattern Recognition · Computer Science 2023-10-19 Zongsheng Yue , Jianyi Wang , Chen Change Loy

In three-dimensional (3D) radiative transfer (RT) problems, the tensor product quadratures are generally not optimal in terms of the number of discrete ray directions needed for a given accuracy of the angular integration of the radiation…

Solar and Stellar Astrophysics · Physics 2020-04-08 Jiri Stepan , Jaume Jaume Bestard , Javier Trujillo Bueno

This work presents an efficient numerical method based on spectral expansions for simulation of heat and moisture diffusive transfers through multilayered porous materials. Traditionally, by using the finite-difference approach, the problem…

Computational Engineering, Finance, and Science · Computer Science 2020-02-20 Suelen Gasparin , Denys Dutykh , Nathan Mendes

Radiative transfer is essential in astronomy, both for interpreting observations and simulating various astrophysical phenomena. However, self-consistent line radiative transfer is computationally expensive, especially in 3D. To reduce the…

Instrumentation and Methods for Astrophysics · Physics 2025-05-14 Thomas Ceulemans , Frederik De Ceuster , Leen Decin

This work presents a detailed mathematical model combined with an innovative efficient numerical model to predict heat, air and moisture transfer through porous building materials. The model considers the transient effects of air transport…

Applied Physics · Physics 2020-02-20 Julien Berger , Denys Dutykh , Nathan Mendes , Bolatbek Rysbaiuly

Context: The solution of the nonlocal thermodynamical equilibrium (non-LTE) radiative transfer equation usually relies on stationary iterative methods, which may falsely converge in some cases. Furthermore, these methods are often unable to…

Solar and Stellar Astrophysics · Physics 2015-07-29 Julien Lambert , Eric Josselin , Nils Ryde , Alexandre Faure

A parametric, hybrid reduced order model approach based on the Proper Orthogonal Decomposition with both Galerkin projection and interpolation based on Radial Basis Functions method is presented. This method is tested against a case of…

Numerical Analysis · Mathematics 2019-12-02 Sokratia Georgaka , Giovanni Stabile , Kelbij Star , Gianluigi Rozza , Michael J Bluck

A class of algorithms for the solution of discrete material optimization problems in electromagnetic applications is discussed. The idea behind the algorithm is similar to that of the sequential programming. However, in each major iteration…

Optimization and Control · Mathematics 2017-07-14 Johannes Semmler , Lukas Pflug , Michael Stingl

Robust and efficient solvers for coupled-adjoint linear systems are crucial to successful aerostructural optimization. Monolithic and partitioned strategies can be applied. The monolithic approach is expected to offer better robustness and…

Numerical Analysis · Mathematics 2023-09-25 Christophe Blondeau , Mehdi Jadoui

Compositional simulation is challenging, because of highly nonlinear couplings between multi-component flow in porous media with thermodynamic phase behavior. The coupled nonlinear system is commonly solved by the fully-implicit scheme.…

Computational Physics · Physics 2020-10-13 Jiamin Jiang , Xian-Huan Wen

A mayor problem that arises in the computation of stellar atmosphere models is the self consistent determination of the temperature distribution via the constraint of energy conservation. The energy balance includes the gains due to the…

Astrophysics · Physics 2007-11-02 Octavio Cardona , Lucio Crivellari , Eduardo Simonneau

Radiative transfer calculations are essential for modeling planetary atmospheres. However, standard methods are computationally demanding and impose accuracy-speed trade-offs. High computational costs force numerical simplifications in…

Earth and Planetary Astrophysics · Physics 2025-11-03 Isaac Malsky , Tiffany Kataria , Natasha E. Batalha , Matthew Graham