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Analytical solutions to the microscopic Boltzmann equation are useful in testing the applicability and accuracy of macroscopic hydrodynamic theory. In this work, we present exact solutions of the relativistic Boltzmann equation, based on a…

Nuclear Theory · Physics 2024-04-15 Shile Chen , Shuzhe Shi

Such problems as computation of spectra of spin chains and vibrational spectra of molecules can be written as high-dimensional eigenvalue problems, i.e., when the eigenvector can be naturally represented as a multidimensional tensor. Tensor…

Numerical Analysis · Mathematics 2019-09-04 Maxim Rakhuba , Alexander Novikov , Ivan Oseledets

We adopt a two-moment formalism, together with a reference-metric approach, to express the equations of relativistic radiation hydrodynamics in a form that is well-suited for numerical implementations in curvilinear coordinates. We…

General Relativity and Quantum Cosmology · Physics 2020-11-11 Thomas W. Baumgarte , Stuart L. Shapiro

We solve Einstein's field equations coupled to relativistic hydrodynamics in full 3+1 general relativity to evolve astrophysical systems characterized by strong gravitational fields. We model rotating, collapsing and binary stars by…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Matthew D. Duez , Pedro Marronetti , Stuart L. Shapiro , Thomas W. Baumgarte

A cutting-edge software is presented to tackle the Newton-Euler equations governing the dynamics of granular flows and dense suspensions in Newtonian fluids. In particular, we propose an implementation of a fixed-radius near neighbours…

Fluid Dynamics · Physics 2022-06-30 Alessandro Monti , Vikram Rathee , Amy Q. Shen , Marco E. Rosti

We introduce and study a new class of kinetic equations, which arise in the description of nonequilibrium macroscopic dynamics of soliton gases with elastic collisions between solitons. These equations represent nonlinear…

Exactly Solvable and Integrable Systems · Physics 2010-09-17 G. A. El , A. M. Kamchatnov , M. V. Pavlov , S. A. Zykov

We propose an extremely versatile approach to address a large family of matrix nearness problems, possibly with additional linear constraints. Our method is based on splitting a matrix nearness problem into two nested optimization problems,…

Numerical Analysis · Mathematics 2025-08-14 Miryam Gnazzo , Vanni Noferini , Lauri Nyman , Federico Poloni

We develop, and implement in a Finite Volume environment, a density-based approach for the Euler equations written in conservative form using density, momentum, and total energy as variables. Under simplifying assumptions, these equations…

Numerical Analysis · Mathematics 2024-05-01 Nicola Clinco , Michele Girfoglio , Annalisa Quaini , Gianluigi Rozza

The shallow water equations are numerically solved to simulate free surface flows. The convective flux terms in the shallow water equations need to be discretized using a Riemann solver to capture shocks and discontinuity for certain flow…

Fluid Dynamics · Physics 2024-10-10 D. Satyaprasad , Soumendra Nath Kuiry , S. Sundar

Recent advances in deep learning have allowed neural networks (NNs) to successfully replace traditional numerical solvers in many applications, thus enabling impressive computing gains. One such application is time domain simulation, which…

Machine Learning · Computer Science 2021-12-09 Samuel Chevalier , Jochen Stiasny , Spyros Chatzivasileiadis

We present two promising applications of training machine learning models inside a differentiable astrophysical (magneto)hydrodynamics simulator. First, we address the problem of slow convergence in hydrodynamical simulations of wind-blown…

Instrumentation and Methods for Astrophysics · Physics 2025-12-09 Leonard Storcks , Tobias Buck

We describe an axisymmetric general relativistic code for rotational core collapse. The code evolves the coupled system of metric and fluid equations using the ADM 3+1 formalism and a conformally flat metric approximation of the Einstein…

Astrophysics · Physics 2009-11-07 Harald Dimmelmeier , Jose A. Font , Ewald Mueller

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

A robust second order, shock-capturing numerical scheme for multi-dimensional special relativistic magnetohydrodynamics on computational domains with adaptive mesh refinement is presented. The base solver is a total variation diminishing…

Astrophysics · Physics 2009-11-13 B. van der Holst , R. Keppens , Z. Meliani

We present an extension of the Piecewise Parabolic Method to special relativistic fluid dynamics in multidimensions. The scheme is conservative, dimensionally unsplit, and suitable for a general equation of state. Temporal evolution is…

Astrophysics · Physics 2009-11-11 A. Mignone , T. Plewa , G. Bodo

A new class of simple and exact solutions of relativistic hydrodynamics is presented, and the consequences are explored in data analysis. The effects of longitudinal work and acceleration are taken into account in an advanced estimate of…

Nuclear Theory · Physics 2008-11-26 T. Csorgo , M. I. Nagy , M. Csanad

A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density…

Nuclear Theory · Physics 2011-08-04 T. Csorgo , M. I. Nagy , M. Csanad

The paper proposes a second-order accurate direct Eulerian generalized Riemann problem (GRP) scheme for the radiation hydrodynamical equations (RHE) in the zero diffusion limit. The difficulty comes from no explicit expression of the flux…

Numerical Analysis · Mathematics 2017-04-03 Yangyu Kuang , Huazhong Tang

The techniques and analysis presented in this thesis provide new methods to solve optimization problems posed on Riemannian manifolds. These methods are applied to the subspace tracking problem found in adaptive signal processing and…

Optimization and Control · Mathematics 2013-05-09 Steven Thomas Smith

A long-standing and formidable challenge faced by all conservative schemes for relativistic magnetohydrodynamics (RMHD) is the recovery of primitive variables from conservative ones. This process involves solving highly nonlinear equations…

Numerical Analysis · Mathematics 2024-04-09 Chaoyi Cai , Jianxian Qiu , Kailiang Wu