A phase-shift-periodic parallel boundary condition for low-magnetic-shear scenarios

PLASMA PHYSICS AND CONTROLLED FUSION 65:1 (2023) ARTN 015016

Authors:

DA St-Onge, M Barnes, FI Parra

Reversible time-step adaptation for the integration of few-body systems

Monthly Notices of the Royal Astronomical Society Oxford University Press 519:3 (2022) 3281-3291

Authors:

Tjarda CN Boekholt, Timothée Vaillant, Alexandre CM Correia

Abstract:

The time-step criterion plays a crucial role in direct N-body codes. If not chosen carefully, it will cause a secular drift in the energy error. Shared, adaptive time-step criteria commonly adopt the minimum pairwise time-step, which suffers from discontinuities in the time evolution of the time-step. This has a large impact on the functioning of time-step symmetrization algorithms. We provide new demonstrations of previous findings that a smooth and weighted average over all pairwise time-steps in the N-body system, improves the level of energy conservation. Furthermore, we compare the performance of 27 different time-step criteria, by considering three methods for weighting time-steps and nine symmetrization methods. We present performance tests for strongly chaotic few-body systems, including unstable triples, giant planets in a resonant chain, and the current Solar System. We find that the harmonic symmetrization methods (methods A3 and B3 in our notation) are the most robust, in the sense that the symmetrized time-step remains close to the time-step function. Furthermore, based on our Solar System experiment, we find that our new weighting method based on direct pair-wise averaging (method W2 in our notation), is slightly preferred over the other methods.

Black Hole Binary Formation in AGN Discs: From Isolation to Merger

ArXiv 2212.06133 (2022)

Authors:

Connar Rowan, Tjarda Boekholt, Bence Kocsis, Zoltán Haiman

An analytical form of the dispersion function for local linear gyrokinetics in a curved magnetic field

ArXiv 2212.02654 (2022)

Authors:

PG Ivanov, T Adkins

Resonant Dynamical Friction: Analytical Description

ArXiv 2211.14784 (2022)

Authors:

Yonadav Barry Ginat, Taras Panamarev, Bence Kocsis, Hagai B Perets