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We present a new method for numerical hydrodynamics which uses a multidimensional generalisation of the Roe solver and operates on an unstructured triangular mesh. The main advantage over traditional methods based on Riemann solvers, which…

Instrumentation and Methods for Astrophysics · Physics 2017-06-28 Sijme-Jan Paardekooper

We present a new computational method for smoothly matching general relativistic ideal magnetohydrodynamics (MHD) to its force-free limit. The method is based on a flux-conservative formalism for MHD and its force-free limit, and a vector…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Vasileios Paschalidis , Stuart L. Shapiro

We present a new open-source axisymmetric general relativistic hydrodynamics code Gmunu (General-relativistic multigrid numerical solver) which uses a multigrid method to solve the elliptic metric equations in the conformally flat condition…

General Relativity and Quantum Cosmology · Physics 2020-09-24 Patrick Chi-Kit Cheong , Lap-Ming Lin , Tjonnie Guang-Feng Li

Direct observations of compact objects, in the form of radiation spectra, gravitational waves from VIRGO/LIGO, and forthcoming direct imaging, are currently one of the primary source of information on the physics of plasmas in extreme…

High Energy Astrophysical Phenomena · Physics 2019-03-27 Fabio Bacchini , Bart Ripperda , Oliver Porth , Lorenzo Sironi

Our contribution concerns with the numerical solution of the 3D general relativistic hydrodynamical system of equations within the framework of the 3+1 formalism. We summarize the theoretical ingredients which are necessary in order to…

Astrophysics · Physics 2007-05-23 J. M. Ibanez , M. A. Aloy , J. A. Font , J. M. Marti , J. A. Miralles , J. A. Pons

A basic leapfrog integrator and its energy-preserving and variational / symplectic variants are proposed and studied for the numerical integration of the equations of motion of relativistic charged particles in an electromagnetic field. The…

Numerical Analysis · Mathematics 2023-04-27 Ernst Hairer , Christian Lubich , Yanyan Shi

This Ph.D. thesis reports on progress in rigorously establishing hydrodynamic principles from the microscopic Hamiltonian dynamics of quantum many-body systems in a general, non-model-specific manner. Using the C*-algebra framework of…

Mathematical Physics · Physics 2026-01-14 Dimitrios Ampelogiannis

We study the variational principle over an Hilbert-Einstein like action for an extended geometry taking into account torsion and non-metricity. By extending the semi-Riemannian geometry, we obtain an effective energy-momentum tensor which…

General Relativity and Quantum Cosmology · Physics 2016-03-30 Jesús Martín Romero , Mauricio Bellini , José Edgar Madriz Aguilar

We present the generalization of a recently introduced modified gravitational potential for self-gravitating fluids. The use of this potential allows for an accurate approximation of general relativistic effects in an otherwise Newtonian…

Astrophysics · Physics 2009-11-13 Bernhard Mueller , Harald Dimmelmeier , Ewald Mueller

We present a new numerical method of special relativistic resistive magnetohydrodynamics with scalar resistivity that can treat a range of phenomena, from nonrelativistic to relativistic (shock, contact discontinuity, and Alfv\'en wave).…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Makoto Takamoto , Tsuyoshi Inoue

In this paper we first propose a framework of structure-preserving submersions, which generalises the concept of a Riemannian submersion, and dualises the concept of subgeometry, or "structure-preserving immersions". The emphasis of our…

Mathematical Physics · Physics 2011-12-30 Ziyang Hu

Starting with a brief introduction into the basics of relativistic fluid dynamics, I discuss our current knowledge of a relativistic theory of fluid dynamics in the presence of (mostly shear) viscosity. Derivations based on the generalized…

High Energy Physics - Phenomenology · Physics 2010-03-02 Paul Romatschke

We construct and study global solutions for the 3-dimensional incompressible MHD systems with arbitrary small viscosity. In particular, we provide a rigorous justification for the following dynamical phenomenon observed in many contexts:…

Analysis of PDEs · Mathematics 2016-03-29 Ling-Bing He , Li Xu , Pin Yu

We investigate a relativistic adaptation of the Lattice Boltzmann Method that reproduces the equations of motion for a turbulent, two-dimensional, massless hydrodynamic system. The classical Lattice Boltzmann Method and its extension to…

Fluid Dynamics · Physics 2024-06-12 Mark Watson

Cosmological simulations involving the fully covariant gravitational dynamics may prove relevant in understanding relativistic/non-linear features and, therefore, in taking better advantage of the upcoming large scale structure survey data.…

General Relativity and Quantum Cosmology · Physics 2017-11-15 David Daverio , Yves Dirian , Ermis Mitsou

Discontinuous Galerkin (DG) methods provide a means to obtain high-order accurate solutions in regions of smooth fluid flow while, with the aid of limiters, still resolving strong shocks. These and other properties make DG methods…

High Energy Astrophysical Phenomena · Physics 2020-12-09 Samuel J. Dunham , Eirik Endeve , Anthony Mezzacappa , Jesse Buffaloe , Kelly Holley-Bockelmann

We assess the suitability of a recent high-resolution central scheme developed by Kurganov & Tadmor (2000) for the solution of the relativistic hydrodynamics equations. The novelty of this approach relies on the absence of Riemann solvers…

Astrophysics · Physics 2009-11-10 Arturo Lucas-Serrano , Jose A. Font , Jose M. Ibanez , Jose M. Marti

A numerical method for integrating the equations describing a dynamically coupled system made of a fluid and cosmic-rays is developed. In smooth flows the effect of CR pressure is accounted for by modification of the characteristic…

Astrophysics · Physics 2008-11-26 Francesco Miniati

Machine learning techniques offer a precious tool box for use within astronomy to solve problems involving so-called big data. They provide a means to make accurate predictions about a particular system without prior knowledge of the…

Instrumentation and Methods for Astrophysics · Physics 2019-01-01 J. Elliott , R. S. de Souza , A. Krone-Martins , E. Cameron , E. E. O. Ishida , J. Hilbe

Context. Recent, nonlinear simulations of wave generation and propagation in full-star models have been carried out in the anelastic approximation using spectral methods. Although it makes long time steps possible, this approach excludes…

Solar and Stellar Astrophysics · Physics 2020-09-15 L. Horst , P. V. F. Edelmann , R. Andrassy , F. K. Roepke , D. M. Bowman , C. Aerts , R. P. Ratnasingam