Modeling Solids in Nuclear Astrophysics with Smoothed Particle Hydrodynamics

TL;DR

This paper introduces a novel 3D SPH simulation approach for modeling neutron star crustal oscillations with material strength, addressing numerical noise issues to improve accuracy in astrophysical solid dynamics.

Contribution

It presents the first implementation of solid material modeling in 3D SPH simulations of neutron star crusts, including techniques to suppress numerical noise.

Findings

Successful simulation of neutron-star crustal oscillations with material strength.

Identification of numerical noise suppression methods for solid SPH simulations.

Demonstration of the importance of noise minimization in accurate crustal dynamics modeling.

Abstract

Smoothed Particle Hydrodynamics (SPH) is a frequently applied tool in computational astrophysics to solve the fluid dynamics equations governing the systems under study. For some problems, for example when involving asteroids and asteroid impacts, the additional inclusion of material strength is necessary in order to accurately describe the dynamics. In compact stars, that is white dwarfs and neutron stars, solid components are also present. Neutron stars have a solid crust which is the strongest material known in nature. However, their dynamical evolution, when modeled via SPH or other computational fluid dynamics codes, is usually described as a purely fluid dynamics problem. Here, we present the first 3D simulations of neutron-star crustal toroidal oscillations including material strength with the Los Alamos National Laboratory SPH code FleCSPH. In the first half of the paper, we present the numerical implementation of solid material modeling together with standard tests. The second half is on the simulation of crustal oscillations in the fundamental toroidal mode. Here, we dedicate a large fraction of the paper to approaches which can suppress numerical noise in the solid. If not minimized, the latter can dominate the crustal motion in the simulations.