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We propose an explicit-implicit scheme for numerically solving Special Relativistic Radiation Hydrodynamic (RRHD) equations, which ensures a conservation of total energy and momentum (matter and radiation). In our scheme, 0th and 1st moment…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Hiroyuki R. Takahashi , Ken Ohsuga , Yuichiro Sekiguchi , Tsuyoshi Inoue , Kengo Tomida

Mixed-frame formulations of radiation-hydrodynamics (RHD), where the radiation quantities are computed in an inertial frame but matter quantities are in a comoving frame, are advantageous because they admit algorithms that conserve energy…

Astrophysics of Galaxies · Physics 2024-11-25 Chong-Chong He , Benjamin D. Wibking , Mark R. Krumholz

We present a divergence-free semi-implicit finite volume scheme for the simulation of the ideal magnetohydrodynamics (MHD) equations which is stable for large time steps controlled by the local transport speed at all Mach and Alfv\'en…

Numerical Analysis · Mathematics 2024-03-08 Walter Boscheri , Andrea Thomann

We present the implementation of an implicit-explicit (IMEX) Runge-Kutta numerical scheme for general relativistic hydrodynamics coupled to an optically thick radiation field in two existing GR-hydrodynamics codes. We argue that the…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Constanze Roedig , Olindo Zanotti , Daniela Alic

For turbulent problems of industrial scale, computational cost may become prohibitive due to the stability constraints associated with explicit time discretization of the underlying conservation laws. On the other hand, implicit methods…

Numerical Analysis · Mathematics 2024-01-31 Carlos A. Pereira , Brian C. Vermeire

We propose a second-order accurate semi-implicit and well-balanced finite volume scheme for the equations of ideal magnetohydrodynamics (MHD) including gravitational source terms. The scheme treats all terms associated with the acoustic…

Numerical Analysis · Mathematics 2023-06-29 Claudius Birke , Walter Boscheri , Christian Klingenberg

In this work we present a proof of concept of CUDA-capable, resistive, multi-fluid models of relativistic magnetohydrodynamics (RMHD). Resistive and multi-fluid codes for simulating models of RMHD suffer from stiff source terms, so it is…

Computational Physics · Physics 2019-01-16 Alex James Wright , Ian Hawke

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

The goal of this paper is to develop 2nd order Implicit-Explicit Runge-Kutta (IMEX-RK) finite volume (FV) schemes for solving 1d parabolic PDEs for option pricing, with possible nonlinearities in the source and advection terms. The spatial…

This paper is concerned about the implicit-explicit (IMEX) methods for a class of dissipative wave systems with time-varying velocity feedbacks and nonlinear potential energies, equipped with different boundary conditions. Firstly, we…

Numerical Analysis · Mathematics 2024-10-29 Zhe Jiao , Yaxu Li , Lijing Zhao

We present Quokka, a new subcycling-in-time, block-structured adaptive mesh refinement (AMR) radiation hydrodynamics code optimised for graphics processing units (GPUs). Quokka solves the equations of hydrodynamics with the piecewise…

Instrumentation and Methods for Astrophysics · Physics 2022-03-02 Benjamin D. Wibking , Mark R. Krumholz

We present the acceleration of an IMplicit-EXplicit (IMEX) non-hydrostatic atmospheric model on manycore processors such as GPUs and Intel's MIC architecture. IMEX time integration methods sidestep the constraint imposed by the…

We describe a new algorithm to solve the time dependent, frequency integrated radiation transport (RT) equation implicitly, which is coupled to an explicit solver for equations of magnetohydrodynamics (MHD) using {\sf Athena++}. The…

Instrumentation and Methods for Astrophysics · Physics 2021-04-07 Yan-Fei Jiang

We present a new implementation of radiation hydrodynamics (RHD) in the adaptive mesh refinement (AMR) code RAMSES. The multi-group radiative transfer (RT) is performed on the AMR grid with a first-order Godunov method using the M1 closure…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Joakim Rosdahl , Jeremy Blaizot , Dominique Aubert , Timothy Stranex , Romain Teyssier

Implicit-Explicit (IMEX) methods are flexible numerical time integration methods which solve an initial-value problem (IVP) that is partitioned into stiff and nonstiff processes with the goal of lower computational costs than a purely…

Numerical Analysis · Mathematics 2026-02-11 Alex C. Fish , Daniel R. Reynolds , Steven B. Roberts

Immersed boundary methods simplify mesh generation by embedding the domain of interest into an extended domain that is easy to mesh, introducing the challenge of dealing with cells that intersect the domain boundary. Combined with explicit…

Computational Engineering, Finance, and Science · Computer Science 2026-01-13 Christian Faßbender , Tim Bürchner , Philipp Kopp , Ernst Rank , Stefan Kollmannsberger

We present an implicit-explicit (IMEX) scheme for semilinear wave equations with strong damping. By treating the nonlinear, nonstiff term explicitly and the linear, stiff part implicitly, we obtain a method which is not only unconditionally…

Numerical Analysis · Mathematics 2024-07-01 Daniel Eckhardt , Marlis Hochbruck , Barbara Verfürth

We propose second-order implicit-explicit (IMEX) time-stepping schemes for nonlinear fractional differential equations with fractional order $0<\beta<1$. From the known structure of the non-smooth solution and by introducing corresponding…

Numerical Analysis · Mathematics 2016-08-03 Wanrong Cao , Fanhai Zeng , Zhongqiang Zhang , George Em Karniadakis

In this article we design a finite volume semi-implicit IMEX scheme for the incompressible Navier-Stokes equations on evolving Chimera meshes. We employ a time discretization technique that separates explicit and implicit terms which…

Numerical Analysis · Mathematics 2023-08-08 Michele Giuliano Carlino , Walter Boscheri

A new class of implicit-explicit (IMEX) methods combined with a p-adaptive mixed finite element formulation is proposed to simulate the diffusion of reacting species. Hierarchical polynomial functions are used to construct an…

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