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This paper can be seen as an attempt of rethinking the {\em Extra-Gradient Philosophy} for solving Variational Inequality Problems. We show that the properly defined {\em Reduced Gradients} can be used instead for finding approximate…

Optimization and Control · Mathematics 2023-12-05 Yurii Nesterov

We have developed a new three-dimensional general relativistic magnetohydrodynamic (GRMHD) code, RAISHIN, using a conservative, high resolution shock-capturing scheme. The numerical fluxes are calculated using the Harten, Lax, & van Leer…

Astrophysics · Physics 2007-05-23 Yosuke Mizuno , Ken-Ichi Nishikawa , Shinji Koide , Philip Hardee , Gerald J. Fishman

A positivity-preserving fractional algorithm is presented for solving the four-equation homogeneous relaxation model (HRM) with an arbitrary number of ideal gases and a liquid governed by the stiffened gas equation of state. The fractional…

Computational Physics · Physics 2022-12-21 Man Long Wong , Jordan B. Angel , Cetin C. Kiris

In this paper, a class of arbitrarily high-order linear momentum-preserving and energy-preserving schemes are proposed, respectively, for solving the regularized long-wave equation. For the momentum-preserving scheme, the key idea is based…

Numerical Analysis · Mathematics 2021-12-07 Chaolong Jiang , Xu Qian , Songhe Song , Jin Cui

We have written and tested a new general relativistic magnetohydrodynamics (GRMHD) code, capable of evolving MHD fluids in dynamical spacetimes with adaptive-mesh refinement (AMR). Our code solves the Einstein-Maxwell-MHD system of coupled…

High Energy Astrophysical Phenomena · Physics 2010-10-27 Zachariah B. Etienne , Yuk Tung Liu , Stuart L. Shapiro

General relativistic magnetohydrodynamic (GRMHD) simulations represent a fundamental tool to probe various underlying mechanisms at play during binary neutron star (BNS) and neutron star (NS) - black hole (BH) mergers. Contemporary…

High Energy Astrophysical Phenomena · Physics 2022-05-27 Jay V. Kalinani , Riccardo Ciolfi , Wolfgang Kastaun , Bruno Giacomazzo , Federico Cipolletta , Lorenzo Ennoggi

A third order shock-capturing numerical scheme for three-dimensional special relativistic magnetohydrodynamics (3-D RMHD) is presented and validated against several numerical tests. The simple and efficient central scheme described in Paper…

Astrophysics · Physics 2009-11-07 L. Del Zanna , N. Bucciantini , P. Londrillo

In this paper, we present a novel hybrid nonlinear explicit-compact scheme for shock-capturing based on a boundary variation diminishing (BVD) reconstruction. In our approach, we combine a non-dissipative sixth-order central compact…

Numerical Analysis · Mathematics 2020-12-21 Amareshwara Sainadh Chamarthi , Steven Frankel

We are interested in the high-order approximation of anisotropic, potential-driven advection-diffusion models on general polytopal partitions. We study two hybrid schemes, both built upon the Hybrid High-Order technology. The first one…

Numerical Analysis · Mathematics 2024-01-25 Simon Lemaire , Julien Moatti

General-relativistic magnetohydrodynamic (GRMHD) simulations are an important tool to study a variety of astrophysical systems such as neutron star mergers, core-collapse supernovae, and accretion onto compact objects. A conservative GRMHD…

High Energy Astrophysical Phenomena · Physics 2018-06-26 Daniel M. Siegel , Philipp Mösta , Dhruv Desai , Samantha Wu

We present a meshless finite difference method for multivariate scalar conservation laws that generates positive schemes satisfying a local maximum principle on irregular nodes and relies on artificial viscosity for shock capturing.…

Numerical Analysis · Mathematics 2025-08-26 Cesare Bracco , Oleg Davydov , Carlotta Giannelli , Alessandra Sestini

In this work, we present a positivity-preserving high-order flux reconstruction method for the polyatomic Boltzmann--BGK equation augmented with a discrete velocity model that ensures the scheme is discretely conservative. Through modeling…

Numerical Analysis · Mathematics 2023-04-19 Tarik Dzanic , Freddie D. Witherden , Luigi Martinelli

We develop a two-dimensional high-order numerical scheme that exactly preserves and captures the moving steady states of the shallow water equations with topography or Manning friction. The high-order accuracy relies on a suitable…

Numerical Analysis · Mathematics 2022-02-24 Victor Michel-Dansac , Christophe Berthon , Stéphane Clain , Françoise Foucher

Hot, diffuse, relativistic plasmas such as sub-Eddington black hole accretion flows are expected to be collisionless, yet are commonly modeled as a fluid using ideal general relativistic magnetohydrodynamics (GRMHD). Dissipative effects…

Instrumentation and Methods for Astrophysics · Physics 2017-03-15 Mani Chandra , Francois Foucart , Charles F. Gammie

We describe a new Godunov algorithm for relativistic magnetohydrodynamics (RMHD) that combines a simple, unsplit second order accurate integrator with the constrained transport (CT) method for enforcing the solenoidal constraint on the…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Kris Beckwith , James M. Stone

We present a new numerical code, ECHO, based on an Eulerian Conservative High Order scheme for time dependent three-dimensional general relativistic magnetohydrodynamics (GRMHD) and magnetodynamics (GRMD). ECHO is aimed at providing a…

Astrophysics · Physics 2009-11-13 L. Del Zanna , O. Zanotti , N. Bucciantini , P. Londrillo

In this paper, we introduce second order and fourth order space discretization via finite difference implementation of the finite element method for solving Fokker-Planck equations associated with irreversible processes. The proposed…

Numerical Analysis · Mathematics 2023-10-12 Chen Liu , Yuan Gao , Xiangxiong Zhang

We propose and analyse a hybrid high-order (HHO) scheme for stationary incompressible magnetohydrodynamics equations. The scheme has an arbitrary order of accuracy and is applicable on generic polyhedral meshes. For sources that are small…

Numerical Analysis · Mathematics 2023-02-21 Jérôme Droniou , Liam Yemm

The paper develops high-order physical-constraint-preserving (PCP) methods for general relativistic hydrodynamic (GRHD) equations, equipped with a general equation of state. Here the physical constraints, describing the admissible states of…

Numerical Analysis · Mathematics 2017-05-10 Kailiang Wu

This paper studies high-order accurate entropy stable nodal discontinuous Galerkin (DG) schemes for the ideal special relativistic magnetohydrodynamics (RMHD). It is built on the modified RMHD equations with a particular source term, which…

Numerical Analysis · Mathematics 2020-10-09 Junming Duan , Huazhong Tang