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The method of moments is widely used for the reduction of kinetic equations into fluid models. It consists in extracting the moments of the kinetic equation with respect to a velocity variable, but the resulting system is a priori…

计算物理 · 物理学 2023-04-05 Michael R. A. Abdelmalik , Zhenning Cai , Teddy Pichard

This paper is concerned with approximations of the Boltzmann equation based on the method of moments. We propose a generalization of the setting of the moment-closure problem from relative entropy to {\phi}-divergences and a corresponding…

数学物理 · 物理学 2015-03-18 M. R. A. Abdel-Malik , E. H. van Brummelen

Moment methods are classical approaches that approximate the mesoscopic radiative transfer equation by a system of macroscopic moment equations. An expansion in the angular variables transforms the original equation into a system of…

数学物理 · 物理学 2023-08-17 Martin Frank , Benjamin Seibold

In this paper we approximate the radiative transfer equations by the method of moments, constructing mesoscopic approximations of arbitrary order of the otherwise microscopic system. To define the necessary closure a minimum entropy…

计算物理 · 物理学 2008-12-17 Philipp Monreal , Martin Frank

This paper presents a numerical approximation technique for the Boltzmann equation based on a moment system approximation in velocity dependence and a discontinuous Galerkin finite-element approximation in position dependence. The closure…

计算物理 · 物理学 2016-02-04 M. R. A. Abdelmalik , E. H. van Brummelen

In this contribution we derive and analyze a new numerical method for kinetic equations based on a variable transformation of the moment approximation. Classical minimum-entropy moment closures are a class of reduced models for kinetic…

数值分析 · 数学 2021-09-22 Tobias Leibner , Mario Ohlberger

Linear stationary reaction-convection-diffusion equations with Dirichlet boundary conditions are approximated using a simple finite difference method corresponding to central differences and the addition of a high-order stabilization term…

数值分析 · 数学 2025-02-07 T. Lewis , X. Xue

Pendry and MacKinnon meaningful discretization of Maxwell's equations was put forward specifically as part of a finite-element numerical algorithm. By contrast with a numerical approach, in the same spirit evoked by the relationships…

光学 · 物理学 2023-03-14 Ovidiu-Zeno Lipan , Aldo De Sabata

A direct numerical solution of the radiative transfer equation or any kinetic equation is typically expensive, since the radiative intensity depends on time, space and direction. An expansion in the direction variables yields an equivalent…

数学物理 · 物理学 2023-10-10 Benjamin Seibold , Martin Frank

Approximate solutions of the chemical master equation and the chemical Fokker-Planck equation are an important tool in the analysis of biomolecular reaction networks. Previous studies have highlighted a number of problems with the…

定量方法 · 定量生物学 2018-05-22 Leo Bronstein , Heinz Koeppl

This paper presents a new method to approximate the time-dependent convection-diffusion equations using conforming finite element methods, ensuring that the discrete solution respects the physical bounds imposed by the differential…

数值分析 · 数学 2025-03-06 Abdolreza Amiri , Gabriel R. Barrenechea , Tristan Pryer

An implicit finite difference method with non-uniform timesteps for solving the fractional diffusion equation in the Caputo form is proposed. The method allows one to build adaptive methods where the size of the timesteps is adjusted to the…

数值分析 · 数学 2024-06-28 Santos B. Yuste , Joaquín Quintana-Murillo

The maximum entropy principle is a powerful tool for solving underdetermined inverse problems. This paper considers the problem of discretizing a continuous distribution, which arises in various applied fields. We obtain the approximating…

数值分析 · 数学 2020-08-05 Ken'ichiro Tanaka , Alexis Akira Toda

This paper contains a study of ADI methods in the presence of charge and current sources. It is shown that there are four significantly distinct cases, with four more related by duality. Of those, only one preserves divergence and, thus, is…

等离子体物理 · 物理学 2015-05-13 David N. Smithe , John R. Cary , Johan A. Carlsson

We suggest the diffuse approach to the relaxation processes within the kinetic theory for the Wigner distribution function. The diffusion and drift coefficients are evaluated taking into consideration the interparticle collisions on the…

核理论 · 物理学 2015-04-02 V. M. Kolomietz , S. V. Lukyanov

The first part of this paper introduces sufficient conditions to determine conservation laws of diffusion equations of arbitrary fractional order in time. Numerical methods that satisfy a discrete analogue of these conditions have…

数值分析 · 数学 2022-03-07 Angelamaria Cardone , Gianluca Frasca-Caccia

By using the Onsager principle as an approximation tool, we give a novel derivation for the moving finite element method for gradient flow equations. We show that the discretized problem has the same energy dissipation structure as the…

数值分析 · 数学 2020-09-04 Xianmin Xu

This paper is devoted to $\phi$-entropies applied to Fokker-Planck and kinetic Fokker-Planck equations in the whole space, with confinement. The so-called $\phi$-entropies are Lyapunov functionals which typically interpolate between Gibbs…

偏微分方程分析 · 数学 2018-08-02 Jean Dolbeault , Xingyu Li

We develop a fully discrete scheme for time-fractional diffusion equations by using a finite difference method in time and a finite element method in space. The fractional derivatives are used in Caputo sense. Stability and error estimates…

偏微分方程分析 · 数学 2019-08-05 Moulay Rchid Sidi Ammi , Ismail Jamiai , Delfim F. M. Torres

Structure-preserving numerical schemes for a nonlinear parabolic fourth-order equation, modeling the electron transport in quantum semiconductors, with periodic boundary conditions are analyzed. First, a two-step backward differentiation…

数值分析 · 数学 2012-08-28 Mario Bukal , Etienne Emmrich , Ansgar Jüngel
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