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We present IAS15, a 15th-order integrator to simulate gravitational dynamics. The integrator is based on a Gau\ss-Radau quadrature and can handle conservative as well as non-conservative forces. We develop a step-size control that can…

Earth and Planetary Astrophysics · Physics 2015-06-22 Hanno Rein , David S. Spiegel

A high-order well-balanced scheme for the Euler equations with gravitation is presented. The scheme is able to preserve a spatially high-order accurate discrete representation of a large class of hydrostatic equilibria. It is based on a…

Numerical Analysis · Mathematics 2018-07-12 Luc Grosheintz , Roger Käppeli

We have designed and developed, from scratch, a global circulation model named THOR that solves the three-dimensional non-hydrostatic Euler equations. Our general approach lifts the commonly used assumptions of a shallow atmosphere and…

Earth and Planetary Astrophysics · Physics 2016-10-05 João M. Mendonça , Simon L. Grimm , Luc Grosheintz , Kevin Heng

We consider the Hirota equation (the discrete analog of the generalized Toda system) over a finite field. We present the general algebro-geometric method of construction of solutions of the equation. As an example we construct analogs of…

Exactly Solvable and Integrable Systems · Physics 2009-11-07 Adam Doliwa , Mariusz Bialecki , Pawel Klimczewski

The formation and evolution of protoplanetary systems, the breeding grounds of planet formation, is a complex dynamical problem that involves many orders of magnitudes. To serve this purpose, we present a new hybrid algorithm that combines…

Earth and Planetary Astrophysics · Physics 2011-06-01 Patrick Glaschke , Pau Amaro-Seoane , Rainer Spurzem

We introduce a hybrid method to couple continuous Galerkin finite element methods and high-order finite difference methods in a nonconforming multiblock fashion. The aim is to optimize computational efficiency when complex geometries are…

Numerical Analysis · Mathematics 2021-11-24 Tuan Anh Dao , Ken Mattsson , Murtazo Nazarov

We study the numerical approximation by space-time finite element methods of a multi-physics system coupling hyperbolic elastodynamics with parabolic transport and modeling poro- and thermoelasticity. The equations are rewritten as a…

Numerical Analysis · Mathematics 2023-02-14 Markus Bause , Mathias Anselmann , Uwe Köcher , Florin A. Radu

We introduce a general framework for the construction of well-balanced finite volume methods for hyperbolic balance laws. We use the phrase well-balancing in a broader sense, since our proposed method can be applied to exactly follow any…

Numerical Analysis · Mathematics 2020-08-05 Jonas P. Berberich , Praveen Chandrashekar , Christian Klingenberg

We present new splitting methods designed for the numerical integration of near-integrable Hamiltonian systems, and in particular for planetary N-body problems, when one is interested in very accurate results over a large time span. We…

Numerical Analysis · Mathematics 2015-04-10 Sergio Blanes , Fernando Casas , Ariadna Farres , Jacques Laskar , Joseba Makazaga , Ander Murua

We present WHFast, a fast and accurate implementation of a Wisdom-Holman symplectic integrator for long-term orbit integrations of planetary systems. WHFast is significantly faster and conserves energy better than all other Wisdom-Holman…

Earth and Planetary Astrophysics · Physics 2015-07-15 Hanno Rein , Daniel Tamayo

We present new almost time-reversible integrators for solution of planetary systems consisting of "planets" and a dominant mass ("star"). The algorithms can be considered adaptive generalizations of the Wisdom--Holman method, in which all…

Earth and Planetary Astrophysics · Physics 2024-04-09 David M. Hernandez , Walter Dehnen

OCTO-TIGER is an astrophysics code to simulate the evolution of self-gravitating and rotat-ing systems of arbitrary geometry based on the fast multipole method, using adaptive mesh refinement. OCTO-TIGER is currently optimised to simulate…

Instrumentation and Methods for Astrophysics · Physics 2021-08-12 Dominic C. Marcello , Sagiv Shiber , Orsola De Marco , Juhan Frank , Geoffrey C. Clayton , Patrick M. Motl , Patrick Diehl , Hartmut Kaiser

Our focus is on simulating the dynamics of non-interacting particles including the effects of an external potential, which, under certain assumptions, can be formally described by the Dean-Kawasaki equation. The Dean-Kawasaki equation can…

Numerical Analysis · Mathematics 2025-11-26 Ana Djurdjevac , Ann Almgren , John Bell

The iterative rational Krylov algorithm (\textsf{IRKA}) is a popular approach for producing locally optimal reduced-order $\mathcal{H}_2$-approximations to linear time-invariant (LTI) dynamical systems. Overall, \textsf{IRKA} has seen…

Numerical Analysis · Mathematics 2019-11-15 C. Beattie , Z. Drmac , S. Gugercin

A novel numerical approach to solving the shallow-water equations on the sphere using high-order numerical discretizations in both space and time is proposed. A space-time tensor formalism is used to express the equations of motion…

Numerical Analysis · Mathematics 2021-11-12 Stéphane Gaudreault , Martin Charron , Valentin Dallerit , Mayya Tokman

Calculating the long term solution of ordinary differential equations, such as those of the $N$-body problem, is central to understanding a wide range of dynamics in astrophysics, from galaxy formation to planetary chaos. Because generally…

Instrumentation and Methods for Astrophysics · Physics 2018-01-23 David M. Hernandez , Edmund Bertschinger

In this paper we study arbitrarily high-order energy-conserving methods for simulating the dynamics of a charged particle. They are derived and studied within the framework of Line Integral Methods (LIMs), previously used for defining…

Numerical Analysis · Mathematics 2019-10-17 L. Brugnano , J. I. Montijano , L. Rández

Context. Integrating the motion of stars in a smoothed potential is necessary in many stellar and galactic studies. Previous works have often used numerical integrators that alternate between linear drifts and velocity kicks (such as the…

Astrophysics of Galaxies · Physics 2025-05-22 Alexandre Bougakov , Melaine Saillenfest , Marc Fouchard

Gravitational wave signals from extreme mass ratio inspirals are a key target for space-based gravitational wave detectors. These systems are typically modeled as a distributionally-forced Teukolsky equation, where the smaller black hole is…

General Relativity and Quantum Cosmology · Physics 2025-09-16 Manas Vishal , Scott E. Field , Katie Rink , Sigal Gottlieb , Gaurav Khanna

A space discretization of an integrable long wave-short wave interaction model, called the Yajima-Oikawa system, was proposed in the recent paper arXiv:1509.06996 using the Hirota bilinear method (see also…

Exactly Solvable and Integrable Systems · Physics 2018-09-18 Takayuki Tsuchida